US2403055A - Circuit breaker - Google Patents

Description

Patented July 2,

cmcm'r'nnmxnn Richardv C. Cunningham, East McKeesport, Pa" asslgnor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application September 15, 1941, Serial No. 410.870 25 175-294) The invention relates to circuit breakers and, more particularly, to circuit breaker operating mechanisms of the produce closing or quick automatic reclosing of the circuit breaker.

Circuit breakers are frequently required for quick automatic reclosing service, and it is particularly desirable that such breakers embody an operating mechanism capable of rapidly reversing the switching movement of the breaker, in order to provide for quick automatic reclosing of the breaker immediately after interruption of the circuit and before the breaker reaches full open position so as to reduce the time the circuit is open as much as possible.

Rapid reversal of the switching movement of the circuit breaker for a quick reclosure, particularly in the case of a large circuit breaker, requires a much greater mechanism eflort than is required for a normal closing operation when the closing movement of the breaker is started at a time when the breaker is at rest in the full open position. For example, a pneumatically operated mechanism having a combination of air pressure and operating piston diameter suitable for quick automatic reclosing and rapid reversal of switching movement would produce too much force for normal closing operations and may cause destructive slamming on normal closing operations. The same condition may also be present in the case of an electrically operated circuit breaker mechanism designed for quick automatic reclosing service.

An object of the invention is the provision of a circuit breaker embodying an operating mechanism operable to effect normal closing of the breaker and also operable to effect quick automatic reclosing operation of the breaker, the mechanism having means for automatically causing a greater closing force to be applied on quick automatic reclosing operations than on normal closing operations.

Another object of the invention is the provision or a circuit breaker embodying an operating mechanism operable to produce normal closing and also quick automatic reclosing of the breaker, with means for reducing the operating force on normal closing operations to prevent destructive slamming of the breaker.

Another object of the invention is the provision of a circuit breaker operating mechanism operable to rapidly reverse the switching movement of the breaker and automatically reclose the breaker after interruption of the circuit and before the breaker reaches full open position, and

type which are operable to a also operable to produce normal closing of the breaker from the full open position, the mechanism having automatically selective means for reducing the operating force on normal closing operations.

Another object or the invention is the provision of a circuit breaker embodying an operating mechanism which is pneumatically operated to produce normal closing of the breaker, and also operated to produce quick automatic reclosing of the breaker by rapidly reversing the switching movement, the mechanism being provided with an automatically selective throttle for reducing the air pressure applied to the operating piston on normal closing operations.

Another object of the invention is the provision of a circuit breaker embodying an operating mechanism which is pneumatically operable to quickly reverse the switching movement of the breaker and quickly automatically reclose the breaker after interruption of the circuit but before the breaker reaches full open position, and which is also pneumatically operable to produce normal closing of the breaker from the full open position, the mechanism being provided with an automatically selective throttle comprising a throttle valve which automatically reduces the air pressure applied to the operating piston on normal closing operations and permits full air pressure to be applied to the piston on quick automatic reclosing operations.

Another object of the invention is the provision of a circuit breaker operating mechanism operated by compressed air to produce normal closing, or quick automatic reclosing of the breaker with rapid reversal of switching movement of the breaker, the mechanism having an automatically selective throttle valve responsive to the position of the operating piston to reduce the air pressure applied to the piston on normal closing operations and to cause full air pressure to be applied to the piston on quick reclosing operations.

The novel features that are considered chara'cterlstic 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 one embodiment thereof when read in conjunction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view of a circuit breaker operating mechanism or the pneumatic type embodying the features of the invention,

the mechanism being shown in the closed position in which the circuit breaker is closed;

Fig. 2 is a fragmentary sectional view taken substantially on the line II--II of Fig. 1 showing the main exhaust valve and its connection to the operating cylinder and to the exhaust pilot valve, the main exhaust valve not being visible in the section of Fig. 1 because it is disposed in front of the plane of the section 01' Fig. 1;

Fig. 3 is a wiring diagram of the electrical control circuits for the circuitbreaker operating mechanism, the circuit breaker and its operating mechanism being shown schematically in this figure; and

Fig. 4 is an enlarged fragmentary sectional view of the mechanism showing the parts in an instantaneous position during the beginningof a normal closing peration of the breaker, the throttle valve having been automatically operated to throttling position.

The invention is illustrated as applied to a circuit breaker operating mechanism of the pneumatic type similar to that disclosed in the copending application of James M. Cumming and Richard C. Cunningham, Serial No. 410,686, filed September 13, 1941, and assigned to the assignee of the present invention.

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 l3. Although illustrated as a single pole circuit breaker, it will, of course, be understood that the breaker may be a multi-pole circuit breaker having a set of contact means 9-il 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 I! by suitable connecting means. The connecting means is represented schematically as comprising a lever is pivoted at 2| on a fixed support, one end of the lever being pivotally connected to the breaker lift r 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 2! 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 lever or latching lever 35 is pivotally mounted at one end on the casting 21. The lever 35 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 3! to the upper end 01' a pair of parallel links ll (only one appearing in Fig. 1) which are in turn pivotally mounted on an ear 43 of the main casting H 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 which rotatably supports a roller 41 disposed between the parallel levers connected by a pivot pin by means 01 a pivot pin 53.

The breaker operating rod 25 is pivotally 48 to an intermediate point of the operating lever 35, the pivot pin 4! extending transversely through the parallel levers I! and engaging an opening in the lower end or the rod 25 which is disposed between the parallel levers, the breaker lever 35 is adapted to be held in the closed position shown in Fig. l to hold the breaker closed by means oi. a high speed latching mechanism comprising a main latch II which is pivoted on the main casting 11 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 lever 35. The latch Si is biased to latch ing position against a stop by means of a spring pressed plunger 51 which engages a pro- Jection 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 58 of the latch 5| by means of a compression spring 6| 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 of the plunger.

The construction of the latch face of the main latch Si 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 27 by means of a. pivot pin 59 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 87 is biased to latching position, as shown in Fig. l, by a compression spring 15 which is seated in a recess in the casting 27! and engages an integral projection of the auxiliary latch. The auxiliary latch 61 is also provided with a projection 1! which extends directly over the upper end of the trip plunger 79 of an electro-magnetic trip device iii. The trip device 81 comprises in addition to the trip plunger 79, an E-shaped core 83 of magnetic material mounted on the casting 21, an energizing winding 85 which is mounted on the center leg of the E-shaped core, and a movable armature 8'! cooperating with the core 83. The trip plunger 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 8i 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 81 is energized, the armature 81 thereof is moved upwardly against the core 83 causing upward movement of This upward movement of the breaker to open circuit position, the operating lever 35 being rotated counterclockwise about its pivoted end by the opening movement of the movement of 41 forces the main latch in a counterclockwise direction asit clears the latch. In order to prevent theauxiliary 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 pivot pin 99. on opposlte sides of the auxiliary latch 61. The holdin: 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 99 of the holding lever. The cross member on the free end of the holding lever 95 is disposed directly beneath the end of the operating lever 35 so that the holding lever is 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 projection IIII of the por-' tion 99 thereof engages and holds the auxiliary latch 91 in unlatched position until the breaker operating lever 35 is returned to closed position and its roller 41 has become reengaged by the latch face of the main latch 5|. For this purpose the biasing spring 91 of the holding lever is or greater strength than the auxiliary latch biasing spring 1'5.

An operating piston I93 having piston rings I95 is movable within the operating cylinder 29 and this piston has a piston rod I91 which slidably extends in a fluid tight manner through an opening provided therefor in the top wall or the cylinder 29. The upper end of the piston rod I91 has a connecting element I99 threadedly connected thereto, which is pivotally connected to the pivot pin 49 carried by the operating lever 35. Thus the operating piston I93 is mechanically connected to the circuit breaker operating rod 25 and operating lever 35. 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 I93 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 III, 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 H3. The opening operation of the main inlet valve is, in turn, controlled by a pilot valve I I5 operated by an electromagnet H1.

The main inlet valve II3 comprises a valve housing II9 which is secured to the side of the main cylinder casting 21 by a plurality of bolts (not shown), and this valve housing is provided with inlet passages I2I and I23, the former communicating with the auxiliary air reservoir III and the latter communicating with an inlet port I25 in the upper end of the main cylinder 29. A main valve element I21 disposed in the valve housing has a stem I29 slidably mounted in a guide sleeve I3I which is carried by a bushing I33. The bushing I33 is threaded in an opening in the valve housing between the passages I2I and I23, and this bushing serves as a valve seat for the valve element I21. The guide sleeve I3I is connected to the bushing I33 by a plurality of spider legs which permit the compressed air to flow through the passages I2I and I23 when the valve is open. The valve element I21 is biased to closed position, as shown in Fig. 1, by means or a helical compression spring I35 which surrounds the guide sleeve I3I. The lower end of the valve biasing spring I35 bears against the spider legs or the bushing I33 and the upper end of the spring bears against a spring support I31 which is secured to the upper end of the valve stem I29.

The auxiliary air tank III is secured to the underside ot the valve housing II9 by means or a plurality of bolts I39 (only one being shown) which extend through the valve housing H9 and engage an annular flange I4I formed on the neck of the air tank III, thereby clamping the flange tightly against the underside of the valve housing II9. A sealing ring I43 is interposed between the valve housing and the flange I of the auxiliary air tank III to tightly seal the Joint therebetween. The auxiliary air tank III is connected to a main air storage tank (not shown) by means of a conduit I45, 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 I41 to admit compressed air into the upper end of the operating cylinder 29 to close or automatically reclose the circuit breaker. The valve piston I41 is movable in a valve cylinder I49 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 the valve biasing spring and is disposed between the underside of the valve piston and a shoulder formed in the valve housing H9.

The valve operating piston I41 is adapted to be moved downwardly to open the main inlet valve, by compressed air from the auxiliary air tank III, through passages I52 and I53 formed in the valve housing I I9, the valve piston I41 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 I52 and I53 communicate with cooperating passages in the pilot valve housing I55 which is secured to the main valve housing II9. Communication between the auxiliary air tank and the upper end or the valve cylinder I49 is normally shut off, however, by a pilot valve I51 disposed in the pilot valve housing I55. The pilot valve I51 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 II1 upon energization thereof.

The cylinder portion I49 of the main inlet valve housing is provided with a plurality of ports I59 (only one being shown) adjacent the lower end of the operating cylinder I49 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 I5I, as the main inlet valve I21 opens. A skirt on the lower end of the valve piscylinder 29 after closing operation.

The electromagnet II1 comprises a frame IBI and a core I" both or magnetic material, an energizing winding I", and a pivoted armature I91. The electromagnet is secured to the pilot valve housing IIB by the lower end of the core Ill being threaded into an opening in the upper end of the pilot valve housing I", thus clamping the winding spool and the irame IBI to the pilot valve housing III, the upper end of the core I63 having a shoulder which bears against a plate I" which rests on the upper end of the winding spool. The armature I91 the electromagnet is pivotally supported on the upper end or the frame I9I, and this armature engages a plunger III which extends slidably through an opening in the center of the core I63, 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 I81 in unattracted position. A casin: I 13 is secured to the plate I69 and frame ISI, for enclosing the armature I61.

When the electromagnet H1 is energized, the armature I61 thereof is moved to attracted position depressing the plunger HI and thereby causing opening of the pilot valve I51 to admit compressed air from the air tank I I I to the upper end of the valve cylinder I49. The compressed air flowing into the upper end oi. the valve cylinder through the passages II 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 I 2I and I23 into the main operating cylinder 29 and quickly moves the operating piston I03 downwardly to closed position, thereby closing the circuit breaker 1. As soon as the electromagnet H1 is deenerglzed, the pilot valve I51 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 I15 extends through the casing I13 of the electromagnet H1 and engages the armature I61. The push button I15 serves as a means for manually opening the pilot valve I91 to cause a closing operation of the circuit breaker. The electromagnet H1 01' the pilot valve III is adapted to be operated electrically to cause closing or automatic reclosing oi the circuit breaker by circuit means which will be hereinafter described.

In order to provide for quick reversal of movement of the operating piston I03 and circuit breaker 1 to provide the etlect of trip tree operation oi the circuit breaker and to also provide for quick reclosing oi the breaker, the operating cylthe completion 01' a normal haust means being 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 in the side wall of the operating cylinder, indicated by the dotted lines 01' Fig. 1. Referring to Fig. 2, the exhaust ports I8I in the side oi the main operating cylinder 29 communicate with an exhaust passage I93 formed in the valve housing I of a main exhaust valve indicated generally at I91 (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,

EXhMJSIi valve I93 disposed within the valve cylinder. per end of the biasing spring I93 bears against the underside of the top oi. the piston valve I89 and the lower end oi the spring bears against the bottom closure plate I95 oi the valve cylinder I9I. annular guide projection I91 is formed integral with the bottom end plate I95 oi. the valve cylinder I9I, and a cooperating cylindrical shaped projection I 99 is formed on the inside of the piston I89. The projections I91 and I9! serve as a guide for the biasing spring I93, and

tum of the annular projection I91 at the end of the opening movement of the exhaust valve I89. The exhaust ports IBI and exhaust passage I83 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 I03 from retarding opening movement of the circuit breaker when the circuit breaker is called upon to open.

Opening of the main exhaust valve I89 is controlled by a pilot valve, indicated generally at 20 I, which is adapted to be operated by the trip de- 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 III.

The exhaust pilot valve comprises a light pilot valve element 203 movable in an opening 204 provided therefor in the pilot valve housing 205 which is formed integral with the main operating cylinder casting 21. The pilot valve element 203 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 201 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 204 is in communication with a passage ZII (Fig. 2) formed in a, closure passage 2I I to a recess 2 I5 in the upper end of the exhaust valve cylinder I9I 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 2I8 when the pilot valve is opened to initiate opening movement of the main exhaust valve I88. As soon as themain exhaust valve I88 is opened a small distance by air pressure through the conduit 2I8, the air pressure flowing from the main operating cylinder 28, through the exhaust passage I88 passes over the top of the main exhaust valve I88 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 I88 until the pressure in the main operating cylinder 28 has collapsed to a predetermined value whereupon the spring I88 immediately recloses the main exhaust valve. The air trapped in the annular projection I81 by the piston type projection I88 assists the spring I88 in quickly returning the main exhaust valve to closed position upon collapse of pressure in the breaker operating cylinder 28. The biasing spring 88 of the trip plunger 18 serves to return the exhaust pilot valve 288 to closed position as soon as the trip device 8I is deenergized.

A port 2I8 is provided in the lower end of the exhaust valve cylinder I8I to permit opening of the piston type main exhaust valve I88, the port 2I8 being opened to the atmosphere to allow air beneath the piston I88 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 I88 to prevent any leakage air pressure from the pilot valve 28I and from the main cylinder 29 from falsely operating the exhaust valve I81. 4

The exhaust ports I8I are located in the side wall of the cylinder 28 at a predetermined point intermediate the end positions of the operating piston I83 so that these exhaust ports will be closed by the main operating piston I83 after the braker has opened a, predetermined distance sufficient 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 I88 on a quick reclosing operation of the mechanism. The closing of the exhaust ports I8I by the piston I88 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 I81 closes.

A pair of auxiliary switch devices 228 and 221 is mounted on a bracket 228 secured to the main casting 21. 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 28I and 288, respectively, whereby the auxiliary switches may be set to operate at predetermined desired points in the operation of the main circuit breaker 1. The operating shaft 23I of the auxiliary switch device 228 is connected by a crank 288 and link 231 to the projection 288 of an auxiliary switch operating lever 2. The lever 24I is pivotally mounted on the fixed pivot pin 88 and the free end of this lever is connected .by a slot 248 to the pivot pin 49 which connects the circuit breaker operating rod 28 to the operating lever 88. The operating shaft 288 of the auxiliary switch device- 221 is also connected, by a crank 248 and a link 241, to the projection 288 of the auxiliary switch operating lever 24I. Thus each of the auxiliary switch devices 228 and 221 is operated by and in accordance with the movement of the circuit breaker 1.

Referring now to Fig. 3 which diagrammatically shows the circuits for electrically controlling the inlet valve electromagnet H1 and the trip device 8I. 28I and 288 designate a pair of supply conductors connected to a source of electric energy (not shown). The winding I88 of the electromagnet II1 which controls the admission of compressed air to the operating cylinder for closing the circuit breaker, is connected in an energizing circuit 288 extending from the supply conductor 28I, through the winding I88 of the electromagnet II1, through back contacts 281 of a release relay 288 and front contacts 28] of an operating relay 288 to the supply conductor 283. The energizing winding of the operating relay 288 is connected in an energizing circuit which extends from the supply conductor 288, through a conductor 288, back contacts 281 of the release relay 288, energizing winding of the operating relay 283, conductor 288, and through a manual control switch 2H for controlling normal closing operation of the circuit breaker, to the supply conductor 28I. The energizing winding of the release relay 288 is connected in an energizing circuit which extends from the supply conductor 283, through an auxiliary switch 218 which is adapted to be closed when the circuit breaker reaches closed position, through a conductor 218, energizing winding of the release relay 288, conductor 211, through the front contacts 218 of the operating relay 283 and through a conductor 218 to the supply conductor 28I.

A stick circuit is provided for maintaining the operating relay 283 energized after a momentary operation of the manual closing control switch 21L This stick circuit extends from the supply conductor 288, through the conductor 288 and. back contacts 281 of the release relay 288, energizing winding of the operating relay 283, and through a conductor 288, conductor 211, front contacts 218 of the operating relay, and conductor 218 to the supply conductor 28I. A locking circuit is also provided for maintaining the release relay 288 energized until the manual closing control switch 2 has been opened. This locking circuit for the relay 288 extends from the supply conductor 288, through a portion of the conductor 288, front contacts 288 of the release relay 288, energizing winding of release relay 288, conductor 283, conductor 288 and the manual closing control switch 2" to the supply conductor 28I.

The winding 88 of the trip device 8| is connected in an energizing circuit which extends from the supply conductor 288, through conductor 281, through an auxiliary switch 288 which is closed when the circuit breaker is closed, conductor 28I, energizing winding 88 of the trip device 8|, conductor 283 and the contacts 288 of a fault responsive relay 281, and through a conductor 288 to the opposite supply conductor 28I. The fault responsive relay 281 is arranged to be operated to close its contacts 288 upon the a predetermined overload, such, for example, as a short circuit in the main circuit I3 controlled by the circuit breaker 1. For this purpose, the energizing winding of the protective relay 281 is arranged to be energized by a current transformer 8M associated with the main circuit conductor l8. Thus when a predetermined overload condition or short circuit occurs in the main circuit l8 controlled by the breaker 1, the fault responsive relay 281 becomes energized a suflicient amount to close its contacts, thereby effecting energlzation of the trip device ll. 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 I may also be tripped open manually by means of a manually operable trip control switch 883 connected in series with a conductor 305 which is arranged to shunt the contacts 285 of the protective relay 281.

The circuit breaker 1 is adapted to be quickly automatically reclosed immediately following interruption of the circuit by the circuit breaker occurrence of a breaker is preferably initiated immediately after the circuit breaker has interrupted the circuit and before the circuit breaker reaches full open position. Reclosing relay 381 has its contacts ll! connected in series with a, conductor 8H which is conneced in shunt relation to the contacts of the manual closing control switch 21i. A manually operable switch III is provided in the conductor 8 for the purpose of preventing quick automatic reclosing operation of the circuit breaker if automatic reclosing is not desired. The energizing winding of the reclosing relay "1 is connected in series in an energizing circuit 5 which extends from the supply conductor 258, through the winding of the energized and closes its contacts 295 to effect energization of the trip device 8|. device 8| is thus energized, it plunger 18 upwardly to cause the 51 to release the main latch 5|, the breaker operating lever breaker is immediately moved to open position by its biasing spring I5. The operation of the trip plunger 19 also opens the pilot valve 203,

When the trip moves the trip auxiliary latch thereby releasing 35.

sure in the cylinder 28 at this time. circuit I8 is interrupted during the first part of of the circuit breaker 1 by the time the circuit breaker has opened through only a part of its full open distance.

Assuming the 1 determined distance, less than the full open distance, Quick automatic reclosing operation of the circuit is accomplished by the reclosing relay 381 in response to closing of its circuit by the contacts 3|8 of the fault responsive relay 281 and closing the adjustable auxiliary switch 1. The contacts MS of the fault responsive relay are closed simultaneously with the contacts 285 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 301. During the initial opening moveand the relay 381 thereupon closes its contacts 388, completing an energizing circuit for the operating relay 282, this energizing circuit extending from the supply conductor 25i, through the contacts 308 of the reclosing relay, conductor 8H, conductor 258, energizing winding of operating relay 288, back 218 and 28!. tacts 2M completes an energizing circuit for the inlet valve controlling electromagnet I I1, through the back contacts 251 of the release relay, and through conductor 255. The electromagnet H1 when energized opens the pilot valve I51, thereby causing opening of the lines R in Fig. 1. As has previously been explained, the exhaust ports iii are located in a position such that they are closed by the operating piston I83 during the prevented and the exhaust valve I85 is given a time interval to mechanically close before the downward movement of the operating piston opens the exhaust ports Ill.

Closing of the contacts 218 of the operating relay 253 prepares an energizing circuit for the release relay 258. This circuit extending from the supply conductor 25I, through conductor 218, 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

compressed air to the operating cylinder 28, and the opening of contacts 261 effects deenergization of the operating relay 263. The closing of the front contacts 285 normally produces no effect during quick automatic reclosing operation,

13 since the contacts 309 or 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 291 is again energized the instant the main circuit is completed again causin energization of the trip device 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 I21 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 32I of any conventional construction may be provided in the circuit of the reclosing relay 301 one attempted quick automatic reclosing operation of the circuit breaker, or to open the quick reclosing circuit and transfer control of the re closing relay to a time delayed reclosing device in a manner well known in the art. It the lockout device 32 I 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 I. 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 26I and 218, the closing of contacts 26I 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 213 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 21I 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 2G3 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 251 and 261, thereby deenergizing the inlet valve controlling electromagnet II1 by the contacts 251 and also deenergizing the operating relay 263 by the contacts 261 and 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 prevent more than 14 to complete a locking circuit for maintaining the release relay energized as long as the manual closing control switch 21I is held closed, this locking circuit extending from the supply conductor 253, through the front contacts 205 and energizing winding of the release relay 259, conductor 203, conductor 269 and manual closing control switch 21I to the supply conductor 25I. 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 8i will be operated to release the latch and cause opening of the exhaust valve so that the breaker will immediately open even though the inlet valve I09 may be open at the time the circuit is completed.

The circuit breaker may be manually tripped open by closin the manual trip control switch 303 which effects energization of the trip device 3| and tripping of the circuit breaker.

The circuit breaker operating mechanism and its electrical control. as thus far described in detail above are similar to that disclosed in the aforementioned copending application of James M. Cumming and Richard C. Cunningham, Serial No. 410,686.

The combination of air pressure and operating piston diameter required to quickly reverse the switching movement and quickly automatically reclose the breaker after interruption of the circuit, and before the breaker reaches full open position, produces an operating force which is much greater than that required for normal closing operations where the breaker is closed from a position at rest in the full open position. Consequently, the extra large force required for quick automatic reclosing may cause destructive slamming of the breaker on normal closing operations. In accordance with one embodiment of the present invention, the operating mechanism is provided with an automatically selective throttle which is automatically effective to throttle or reduce the air pressure applied to the operating piston on normal closing operations, but which allows the application of full air pressure to the operating piston on quick reclosing operations.

The automatically selective throttle comprises a throttle valve 325 of the gate type which is slidably mounted in an opening 321 provided therefor in the inlet valve housing H9. The opening 321 is disposed transverse to the air inlet passage I23 at a point between the main inlet valve I21 and. the inlet port I25 of the operating cylinder. The upper end of the opening 321 is closed by a plate 329 secured to the top of the valve housing H9 by cap screws 33I (only one being shown). The throttle valve is slidable up or down in the opening 321 to either fully open or partially close the air inlet passage I23. A spring 333 biases the throttle valve 325 upwardly to its open or nonthrottling position shown in Fig. 1. In this position, the throttle valve 325 allows full air pres-- sure to be applied to the breaker operating piston when the main inlet valve I21 is opened to produce quick automatic reclosing of the breaker. The throttle valve is adapted to be moved downwardly to a predetermined partially closed or throttling position, as shown in Fig. 4, by a small piston 335 which is movable in a cylinder 331 formed in the valve housing H9. In the partially closed or throttling position, as shown in Fig. 4, the throttle valve acts to restrict or reduce the air pressure applied to the breaker operating piston I03 on normal closing operations. The piston 335 is directly connected by a rod 339 to the throttle valve 325. and the valve biasing spring 333 is a helical compression spring disposed in the lower portion of the cylinder 331 between the bottom of the piston 335 and a closure plug 34I threaded into the lower end of the cylinder 331. An adjustable screw 343 extending upwardly through the closure plug 34I- is provided for adjusting the degree of throttling to be produced by the throttle valve 325 on normal closing operations of the breaker.

The throttle valve is adapted to be automatically controlled in accordance with the position of the breaker operating piston I03 at the time the main inlet valve I2! is opened, so that the throttle valve will remain in full open position on a quick automatic reclosing operation where the reclosing movement is initiated when the breaker is only partly open and the operating piston is in a position such as indicated by the dotted lines represented at "R" in Fig. 1, and so that the throttle valve is caused to assume and remain in throttling position, as shown in Fig. 4, on normal closing operations where the breaker is closed from the full open position starting with the operating piston in its uppermost position, as indicated by the dotted lines represented at C in Fig. 1. In order to thus make the throttle valve automatically selective. a pair of auxiliary air passages 345 and 341 are provided, each of which connects the main operating cylinder 29 with the throttle valve cylinder 331. The passage 345 is located adjacent the upper end of operating cylinder 29 and communicates with the upper nd cylinder 33'! above the piston 335. air passage 34! is located and in a position to be closed by the throttle valve piston when that piston is moved downwardly. The arrangement of the passages is such that on normal closing operations, which always start with the breaker piston I03 in its uppermost position C, as soon as the air pressure starts the downward movement of the operating piston, this piston uncovers the exhaust passage 345, as shown in Fig. 4, and consequently the air pressure is admitted through the passage 345 to the upper side of the throttle valve piston 335 and quickly moves the piston 335 downwardly, since at this time the lower portion of the throttle valve cylinder 33] below the piston 335 is open to the atmosphere because the breaker operating piston is above the air passage 341. Downward movement of the piston 335 moves the throttle valve to the throttling position shown in Fig. 4 and maintains it in such position until the air pressure is cut off, due to the fact that the piston 335 closes the air passage 34] and passes below this passage before the breaker operating piston I03 passes below the passage 341. Thus reduced air pressure is applied to the breaker operating piston I03 on all normal closing operations. When the air pressure is cut oil near the end of the closing stroke. and the pressure in cylinder 29 drops, the throttle valve spring 333 returns the throttle valve to its more widely open position where it remains while the breaker is in closed position and during the next opening stroke. On a quick automatic reclosing operation, the inlet valve is opened during an intermediate portion of the opening stroke 01' the breaker, admitting air .pressure to the operating cylinder during the opening stroke when the operating piston I03 is in a position such as indicated by the dotted lines R in Fig. 1. Under these conditions, both passages 345 The other below the passage 345 01 the throttle valve 16 and 341 are open to the high pressure, thus preventing operation of the throttle valve piston 335 since at this time the valve piston 335 is disposed above the passage 34! and below the passage 345. The small pressure difl'erential, due to leakage through the bleeder port 343 in the valve cylinder 331, is insuillcient to overcome the throttle valve biasing spring 333. Consequently, the throttle valve remains in full open position, as shown in Fig. 1, during quick automatic reclosing operations so that full air pressure is applied to the breaker operating piston. The fact that the throttle valve is in widely open position during the opening stroke makes any movement of the partially closed during a stroke.

Thus, to summarize, the throttle valve is in partially closed position during at least the early and intermediate portions of a normal full closing stroke to limit the energy imparted to the piston and contacts, but the valve is in a more widely open position during the intermediate portion of the opening stroke so that if a quick reclosing operation is then initiated, a large force is available for reversing the movement and closing the circuit breaker.

While the invention has been disclosed in ac cordance with the provisions of the 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. It is desired, therefore, that the language normal full closing the prior art.

I claim as my invention:

1. In combination, a circuit breaker, operating mechanism for said breaker, power means for actuating said mechanism to close the breaker, said operable to eifect normal the breaker and also operopen position, and automatically selective means for causing a greater average closing force to be applied to said breaker on a quick automatic reclosing operation during that portion of the closing stroke traversed on quick automatic reclosing operation than during the same portion of the closing stroke on normal closing operation.

2. In combination, a circuit breaker movable to open and to closed circuit position, power operated means for actuating said breaker to closed position, said power operated means being operable to effect normal closing operation of the breaker from full open position of the breaker and also being operable to effect quick automatic reclosing operation of the breaker after interruption of the circuit and before the breaker reaches full open position, and means automatically operable to'cause a greater average closing force to be applied to said breaker on a quick reclosing operation during that portion of the closing stroke traversed on quick automatic reclosing operation than during the same portion of the closing stroke on normal closing operation.

3. In combination, a circuit breaker movable to open and to closed circuit position, operating mechanism for said breaker, power means on- 17 erable to cause said mechanism to effect normal closing operation of the breaker from the full open position of the breaker, said power means also being operable during opening of the breaker to cause said mechanism to initiate quick automatic reclosing of the breaker at a point in the opening stroke intermediate the open and closed positions of the breaker, and means automatical ly operable to cause a greater average closing force to be applied to said breaker on a quick automatic reclosing operation during that portion of the closing stroke traversed on quick automatic reclosing operation than during the same portion of the closing stroke on normal closing operation.

4. In combination, a circuit breaker movable to open and to closed circuit position, operating mechanism for opening and for closing said breaker, means for causing automatic opening of said breaker in response to predetermined overload conditions in the circuit, power means operable to cause said mechanism to effect normal closing of the breaker from the full open position of the breaker,'said power means also being operable during opening of the breaker to cause said mechanism to initiate quick automatic reclosing of the breaker at a point in the opening stroke intermediate the full open and closed positions of the breaker, and means automatically operable to cause said power means to apply a greater average closing force to said mechanism on a quick automatic reclosing operation during that portion of the closing stroke traversed on quick automatic reclosing operation than during the same portion of the closing stroke on normal closing operation.

5. In combination, a circuit breaker movable to open and to closed circuit position, operating mechanism for opening and for closing said breaker, means operable to cause opening of the breaker in response to predetermined overload conditions in the circuit, power means operable during opening of the breaker to apply a closing force to said mechanism to initiate quick automatic reclosing of the breaker before the breaker reaches full open position, said power means also being operable to cause said mechanism to effect normal closing of the breaker from the full open position thereof, and means automatically operable to reduce the average closing force applied to said breaker on normal closing operations during that portion of the closing stroke which constitutes the total closing stroke that is traversed during a quick automatic reclosing operation.

6. In combination, a circuit breaker movable to open and to closed circuit position, fluid pressure operated means for closing said breaker, a source of fluid under pressure, means including a valve operable to connect said fluid pressure operated means to said source of fluid pressure to close the breaker, means for operating said valve to effect normal closing operation of the breaker, and means for operating said valve to effect quick automatic reclqsing operation of the breaker after the circuit is interrupted and, at least by the time the breaker reaches open position, and means for automatically varying the flow of fluid to said fluid pressure operated means, said means for varying the flow of fluid being operable to reduce the average fluid pressure applied to said fluid operated means on normal closing operations as compared to the average fluid pressure applied during quick automatic reclosing operations.

7. In combination, a circuit breaker movable to open and to closed circuit position, fluid pressure operated means for closing said breaker, a source of fluid under pressure, means including a valve for connecting said fluid pressure operated means to said source of fluid pressure to close the breaker, means for operating said valve to effect normal closing operation of the breaker from the full open position, and means for operating said valve to effect quick automatic reclosing of the breaker after interruption of the circuit and before the breaker reaches full open position, and means comprising a throttle means operable to reduce the fluid pressure applied to said fluid operated means during at least a substantial portion of the closing stroke on normal closing operations, said means comprising said throttle means being ineffective to reduce the fluid pressure applied to said fluid pressure operated means on quick automatic reclosing operations.

8. In combination, a circuit breaker movable to open and to closed circuit position, fluid pressure operated means operable to close the breaker, means to cause opening of the breaker in response to predetermined overload conditions, a source of fluid under pressure, means including a valve operable to connect said fluid pressure operated means to said source of fluid pressure to close the breaker, means for operating said valve to effect a normal closing operation of the breaker from the full open position of the breaker, means for operating said valve to effect quick automatic reclosing operation of the breaker during opening of the breaker before said breaker reaches full open position, and means automatically operable to cause a greater fluid pressure to be applied to said fluid pressure operated means on quick automatic reclosing operations than during a portion of the closing stroke on normal closing operations.

9. In combination, a circuit breaker movable to open and to closed circuit position, fluid pressure operated means operable to move the breaker to closed position, means operable to cause opening of the breaker in response to predetermined overload conditions in the circuit, a source of fluid under pressure, means including variable oriflce valve means operable to connect said fluid pressure operated means to said source of fluid pressure to close the breaker, means for operating said valve means to effect normal closing operation of the breaker from the full open position of the breaker, means for operating said valve means to initiate quick automatic reclosing operation of the breaker during opening thereof, and said valve means being operable in response to a quick automatic reclosing operation to cause a greater rate of fluid flow to said fluid pressure operated means on quick reclosing operations thereof than during at least a portion of the closing stroke on normal closing operations.

10. In combination, a circuit breaker movable to open and to closed circuit position, fluid pressure operated means for moving the breaker to closed position, means for biasing said breaker to open position, latching means for holding said breaker closed, tripping means operable to cause said latching means to release the breaker and thereby cause opening of the breaker, a source of fluid under pressure, means including a valve operable to connect said fluid pressure operated means to said source of fluid pressure to close the breaker, means for operating said valve to effect normal closing operation of the breaker from the full open position, means for operating said valve 2,4os,oss

to eflect the initiation of quick automatic reclosing operation of the breaker during the opening stroke before the breaker reaches i'ull open position, and means automatically operable to cause greater fluid pressure to be applied to said fluid pressure operated means on quick reclosing oper- 'ations of the breaker than during a portion of the closing stroke on normal closing operations.

11. In combination, a circuit breaker movable to open and to closed circuit. position, fluid pressure operated means for moving said breaker to closed position, means operable to cause opening of the breaker in response to predetermined overload conditions in the circuit. a source of fluid under pressure, means including a valve for connecting said fluid pressure operated means to said source of fluid pressure to close the breaker, means for operating said valve to eflect normal closing operation of the breaker from the full open position, means for operating said valve to effect the initiation of quick automatic reclosing operation of the breaker during the opening stroke thereof before the breaker reaches full open position, and means for automatically varying the flow of fluid under pressure to said fluid pressure operated means, said means for varying the flow of fluid being operable to cause greater fluid pressure to be applied to said fluid pressure operated means on quick automatic reclosing operations than during at least a portion of the closing stroke on normal closing operations.

12. In combination, a circuit breaker movable to open and to closed circuit position, fluid pressure operated means for moving said breaker to closed position, means operable to cause opening of the breaker in response to predetermined overload conditions in the circuit, a source of fluid under pressure, means including a valve for connecting said fluid pressure operated means to said source of fluid pressure to close the breaker, means for operating said valve to eii'ect normal closing operation of the breaker from the full open position, means for operating said valve to effect the initiation of quick automatic reclosing operation of the breaker during the opening stroke thereof before the breaker reaches full open position, and means comprising an automatically operable throttle valve operable to reduce the fluid pressure applied to said fluid pressure operated means on normal closing operations.

13. In combination, a circuit breaker movable to open and to closed circuit position, operating mechanism therefor comprising an operating cylinder, a piston in said cylinder for moving said breaker to closed position, a source of air under pressure, means including a valve operable to connect one end of said cylinder to said source of air under pressure to close the breaker, means operable in response to the occurrence of predetermined overload conditions in the circuit to cause openin of the breaker, means for operating said valve to effect a normal closing operation or the breaker from the full open position, means for operating said valve to effect the initiation of quick automatic reclosing operation of the breaker during the opening stroke of the breaker before the breaker reaches full open position, and means automatically operable to cause greater air pressure to be applied to said operating piston on quick automatic reclosing operation than during at least a portion of the closing stroke on normal closing operations.

14. In combination, a circuit'breaker movable to open and to closed circuit position, operating mechanism therefor comprising an operating cyltiation of quick automatic reclosing operation of the breaker during the opening stroke of the breaker before the breaker reaches full open position. and means comprising an automatically operable throttle valve operable to automatically reduce the air pressure admitted to said cylinder on normal closing operations.

15. In combination, a circuit breaker movable to open and to closed circuit position, operating mechanism therefor comprising an operating cylinder, an operating piston in said cylinder operable to move said breaker to closed position, a source of air under pressure, means including a valve operable to connect one end of said cylinder to said source of air under pressure to cause closing of the breaker, means operable in response to predetermined overload conditions in the circuit to cause opening of the breaker, means for operating said valve to efi'ect normal closing operation of the breaker, means for operating said valve to effect the initiation of quick automatic reclosing operation of the breaker during the opening stroke before the breaker reaches full open position, a throttle valve in the connection between said cylinder and said source of air under pressure and means for automatically causing said throttle valve to assume a predetermined throttling position during at least a portion of the closing stroke on normal closing operations and a non-throttling position on quick automatic reclosing operations of the breaker.

16. In combination, a circuit breaker movable to open and to closed circuit position, operating mechanism therefor comprising an operating cylinder, an operating piston in said cylinder operable to move the breaker to closed position, a source oi air under pressure, an air inlet connection between said source of air pressure and one end of said cylinder, a valve in said connection operable to admit air under pressure into said one end of the cylinder to close the breaker, means operable in response to predetermined overload conditions in the circuit to cause opening of the breaker, means for operating said valve to effect normal closing operation of the breaker from the full open position, means for operating said valve to admit air under pressure to said end of the cylinder during the opening stroke of the breaker to initiate quick automatic reclosing operation of the breaker from a position intermediate the full open and closed position thereof, an automatically selective throttle valve in said inlet connection automatically operated by air pressure in said cylinder to reduce the air pressure applied to said operating piston on normal closing operations.

17. In combination, a circuit breaker movable to open and to closed circuit position, operating mechanism therefor comprising an operating cylinder, an operating piston in said cylinder operable to move the breaker to closed position, a source of air under pressure, an air inlet connection between said source of air pressure and one end of said cylinder, a valve in said connection operable to admit air under pressure into said one end of the cylinder to close the breaker, means operable in response to predetermined overload conditions in the circuit to cause opening of the breaker, means for operating said valve to effect normal closing operation of the breaker from the full open position, means for operating said valve to admit air under pressure to said end of the cylinder during the opening stroke of the breaker to initiate quick automatic reclosing operation of the breaker from a position intermediate the full open and closed position thereof, a throttle valve in said inlet connection, a cylinder having a piston therein connected to said throttle valve for operating said throttle valve, a spring for biasing said throttle valve to non-throttling position, and a pair of air passages connecting predetermined points of said throttle valve cylinder to predetermined points of said breaker operating cylinder to cause said throttle valve to remain in non-throttling position on quick automatic reclosing operations and to assume a throttling position to reduce the air pressure applied to said breaker operating piston on normal closing operations.

18. In combination, a circuit breaker movable to open and to closed circuit position, operating mechanism therefor comprising an operating cylinder, an operating piston in said cylinder operable to move the breaker to closed position, a source of air under-pressure, an air inlet connection betweensaid source of air pressure and one end of said cylinder, a valve in said connection operable to admit air under pressure into said one end of the cylinder to close the breaker, means operable in response to predetermined overload conditions in the circuit to cause opening of the breaker, means for operating said valve to effect normal closing operation of the breaker from the full open position, means for operating said valve to admit air under pressure to said end of the cylinder during the opening stroke of the breaker to initiate quick automatic reclosing operation of the breaker from a position intermediate the full open and closed position thereof, an automatically selective throttle valve in said inlet connection, a cylinder having a piston therein connected to said throttle valve for operating the valve, a spring for biasing said throttle valve to non-throttling position, an air passage connecting one end of said throttle valve cylinder with said one end of said operating cylinder, a second air passage communicating at one end with the throttle valve cylinder at a point which is on the other side of the throttle valve piston from said first passage when said throttle valve is in non-throttling position, said second passage communicating at its other end with said breaker operating cylinder at a point such that it is closed by said breaker operating piston when the breaker is in full open position, said throttle valve remaining in non-throttling position on quick automatic reclosing operations of the breaker and being moved to a throttling position to reduce air pressure applied to the breaker operating piston on normal closing operations.

19. In combination, a circuit breaker having relatively movable contacts, a fluid motor operatively related to the movable contact, a source of fluid under pressure, a connection including control valve means for admitting fluid from said source to said motor to cause closing operation of the breaker, and means for operating said control valve means to restrict flow of fluid to the fluid motor during at least an early part of full 22 strokes of the fluid motor in closing the breaker and to permit a greater flow of fluid during at least the latter portion of said early part of the stroke upon partial strokes of the fluid motor in closing the breaker,

20. In combination, a circuit breaker havin relatively movable contacts, operating means therefor comprising an operating cylinder, an operating piston in said cylinder operatively related to the movable contact, a source of fluid under pressure connected to said cylinder, control valve means in said connection for admitting fluid from said source to said cylinder to cause said piston to effect closing of said circuit breaker, and means for automatically operating said control valve means to vary the flow of fluid to said cylinder in accordance with whether said piston makes a fullor a partial closing stroke.

21. In combination, a circuit breaker having relatively movable contacts, a fluid motor comprising a cylinder and an operating piston therein operatively related to the movable contact, a source of fluid under pressure, means interconnecting the motor to said source for closing the circuit breaker, a control valve in said interconnecting means operable to admit fluid from said source to said motor to efiect closing operation of the breaker, and variable orifice means interposed in said interconnecting means controlled in accordance with whether said operating piston makes a full or a partial closing stroke for varying the flow of fluid to said cylinder to vary the closing force applied to the piston.

22. In an electric circuit breaker comprising a plurality of relatively movable contacts, a fluid motor including a piston for producing relative movement between said contacts, a source of fluid under pressure, means for interconnecting said source and said fluid motor, and fluid actuated valve means for varying the flow of fluid between said source and said fluid motor during an operating stroke of said circuit breaker, said fluid actuated valve means including a second piston and means for controlling the flow of fluid which actuates said second piston in response to the operating stroke of the circuit breaker, and said fluid motor being so constructed and arranged with reference to said fluid actuated valve means as to permit said fluid under pressure to act initially on substantially the entire working face of said piston of the fluid motor.

23. In an electric circuit breaker comprising a pair of relatively movable contacts, a fluid motor having a piston for operating said circuit breaker, a source of fluid under pressure, means including a main valve for controlling the flow of fluid between said source and said motor to produce relative movement between said contacts, fluid actuated throttle valve means interposed between said main valve and said fluid motor, and one or more fluid passages extending from said fluid motor to said fluid actuated throttle valve for actuating the throttle valve in response to movement of said piston with respect to said one or more fluid passages and said actuation of the throttle valve varying the amount of fluid supplied to the fluid motor during the time said fluid motor produces relative movement between said contacts, said fluid actuated throttle valve means being incapable of transmitting substantially any force from said fluid under pressure acting thereon to said fluid motor.

24. In an electric circuit breaker comprising a plurality of relatively movable contacts, a fluid and said fluid motor and actuated in response to movement of said piston across said one or more iluid passages for preventing excessive acceleration of the movable parts 01' said circuit breaker during the initial part of the closing operation. said fluid motor being so constructed and arranzed with reference to said last-mentioned means as to permit said fluid under pressure to act initially on substantially the entire workin: face 01' said piston. s

25. In a fluid-actuated electric circuit breaker mprising a plurality oi relatively movable con- RICHARD C. UNNINGHAM.

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