US2399328A

US2399328A - Circuit breaker

Info

Publication number: US2399328A
Application number: US499800A
Authority: US
Inventors: James M Cumming
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1943-08-24
Filing date: 1943-08-24
Publication date: 1946-04-30
Anticipated expiration: 1963-04-30

Description

pril 30, A1946'. n J. M. CUMMING 2,399,328

CIRCUIT BREAKER Filed Aug. 24, 1943 Patented Apr. 30, 1946 CIRCUIT BREAKER James M. Cumming, Turtle Creek, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 24, 1943, Serial No. 499,800

11 Claims.

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

Circuit breakers for electrical power systems are desired which operate at very high speed and in which the motion of the parts can be quickly reversed in order to obtain quick interruption and quick reclosing of the electrical circuit. It is, therefore, highly desirable to eliminate as farr as possible the factors which tend to delay operation of the breaker. Where a. pneumatic type operating mechanism is employed for operating a circuit breaker, back pressure in the cylinder tends to retard the speed of operation and some means must be provided to quickly remove the back pressure. The valve means for controlling fluid ow should provide for adequate fluid flow and should operate very quickly despite the.I limitation of small available electrical control energy. The usual types of three-Way valves for admitting iiuid pressure to the cylinder and venting the cylinder have no-t 'been found satisfactory for pneumatic circuit-breaker operating mechanisms for various reasons. They are too slow in operation, do not provide adequate intake and exhaust flow, and require too much electrical control energy.

An object of the present invention is the provision of a circuit breaker with an improved operating mechanism of the pneumatic type capable of eecting quick high-speed operation of the circuit breaker and moving parts.

VAnother object of the invention is the provision of a circuit-breaker operating system of the pneumatic type embodying an improved quickacting intake and exhaust valve-mechanism whereby quick response and high-speed operation of the circuit breaker and its operating means are obtained.

Another object of the invention is the provision of a circuit-breaker operating mechanism of the pneumatic type with an improved quick-acting automatic intake and exhaust valve-mechanism, of simple and inexpensive construction, which provides for high-speed operation and reversal of the operating mechanism and which requires only a small amount of electrical control energy.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The structure and mode of operation of the invention, 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 drawing, in which:

Figure l is a view, partly in section, of a circuit-breaker operating mechanism embodying the present invention, the circuit breaker being shown somewhat schematically, and

Fig. 2 is a fragmentary view, partly in section, showing the dump-valve which is controlled by the trip device.

The present invention is illustrated as applied to a pneumatic circuit-breaker operating mechanism 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 same assignee as the present invention.

Referring to Fig. 1 of the drawing, the circuit breaker represented very schematically at 1, may be of any conventional type either of the oil break, air break or gas blast type. As schematically shown, the circuit breaker comprises stationary contact means 9, and cooperating movable contact means Il. The circuit breakerA is biased to open-circuit position by spring means I5, and is operatively related to the operating mechanism indicated generally at l 'l by any suitable connecting means represented schematically as comprising a lever I9 pivoted at 2l and pivotally connected at one end to the breaker rod 23 and at its other end to an operating rod 25 which is in turn connected to the operating mechanism I1.

The operating mechanism comprises a main casting 21 'formed to provide a cylinder 29 which is closed at its upperend by an integral part of the casting. A closure member 3l is secured to the bottom of the cylinder, this closure member having a relativelylarge port 33 therein open to the atmosphere. An operating or latching lever 35 consisting of a pair of spaced parallel levers is pivotally mounted at one end on the casting 21 by means of a pair of links 4| pivoted on the casting by a pivot-pin 44. Only one of the links 4| and one of the parallel levers is visible in Fig. 1. Part of the operating lever and part of the cylin der casting'have been broken away to reduce the width of the figure. The free ends oi the parallel levers comprising the operating lever 35 are connected by a cross member and carry a short shaft therebetween on which is rotatably mounted a latching roller 41.

The breaker-operating rod 25 is pivotally connected by a pivot pin 49 to the midpoint of the operating lever 35. The breaker-operating lever is adapted to be held in closed position to hold the circuit breaker closed by means of a highspeed latching mechanism comprising a main latch 5I of the slip-ofi type, and an auxiliary holding latch 61. The main latch 5I is pivoted on the casting 21 by a pivot pin 53 and its latch end is adapted to engage the latch roller 41 of the breaker operating lever 35. The latch 5I is biased to latching position by a spring-pressed plunger 51. The auxiliary latch 61 is pivoted on the casting by a pivot pin 69 and is biased by a spring 15 to engage and hold the main latch in latching position. A projection 11 of the auxiliary latch extends directly over the upper end of the trip plunger 19 of an electromagnetic trip device 8 I.

The trip device 8| comprises, in addition vto the trip plunger, an E-shaped core 83 of magnetic material, an energizing winding 85 mounted on the center leg of the core, and a movable armature 81 for moving the trip plunger upwardly to release the latching means and thereby trip open the circuit breaker.

The trip plunger slidably extends upwardly through a guide opening in the center leg of the core 83 and through an opening in the horizontal shelf portion of the casting 21 on which the core 83 is supported by brackets. A spring 89 biases the armature 81 downwardly to unattracted pcsition.

The trip device 8| may be energized by a conventional trip circuit upon the occurrence of predetermined abnormal conditions such as an overload in the circuit controlled by the breaker and also by a manual trip control switch. When the trip device is energized. the armature is moved upwardly causing the trip plunger 19 t0 disengage the auxiliary latch 61 from the main latch 5I whereupon the accelerating spring I5 moves the circuit breaker to open position at high speed. A balance lever 95 pivoted on the pivot pin E3 is provided for holding the auxiliary latch 61 in released position as shown as long as the operating lever 35 is away from the latched position, so that the latch roller 41 can push back and pass the main latch 5| when the circuit breaker is reclosed. The balance lever 95 is biased in a counterclockwise direction by a spring 91, stronger than the auxiliary latch spring 15. and has a projection 99 which extends beneath the auxiliary latch extension 11. The balance lever also has a projection I0! which is adapted to be engaged by the free end of the breaker-operating lever 35 to hold the balance lever down in inoperative position when the operating lever is in closed and latched position.

An operating piston |03 is reciprocably movable i in the operating cylinder 29, and this piston has a piston rod |01 which slidably extends in a fluidtight manner through an opening provided therefor in the top wall of the cylinder. The upper end of the piston rod has a connecting element |09 pivotally connected to the pivot pin 49 on the breaker-operating lever 35. The piston ID3 is thus operatively connected to the circuit breaker and operating lever.

The operating piston |03 is adapted to be moved downwardly in the cylinder 29 to close or automatically reclose the circuit breaker, by compressed gas such as compressed air stored in an auxiliary air reservoir or tank III. Compressed air from the tank I II is admitted into the upper end of the cylinder 29 by a control valve device indicated generally at II3 which will be hereinafter described Compressed air is stored and maintained at a predermined pressure in the tank I I I from a large main reservoir (not shown) supplied by a conventional motor-driven compressor unit (not shown) In order to provide for quick reversal and very high-speed initial opening movement of the operating piston |03 and circuit breaker 'I to provide the effect of trip-free operation of the circuit breaker, the mechanism may be provided with an air-pressure dumping means similar to that disclosed in the aforementioned copending application of J. M. Cumming and R. C. Cunningham. Serial No. l210,686. The air-pressure dumping means causes quick collapse of air pressure in the cylinder on the working side oi the piston whenever the trip device 8| is operated, by instantaneously dumping the pressure air in the cylinder to atmosphere to thereby permit duick reversal and high-speed initia1 opening movement of the circuit breaker unirnpeded by back pressure. The air-pressure dumping means comprises large air pressure dumping ports I I5 in the side wall of thc cylinder 23 at a point substantially midway between the end positions of the piston |03. These ports are adapted to be connected to atmosphere through a passage formed in a dump valvehousing I|1 (Fig. 2) secured to the cylinder 29. This dumping passage is normally closed by a piston type pneumatically-operated dump Valve II9 which is slidably mounted in a valve cylinder I2I formed in the dump-valve housing Ii'I. The dump valve II9 is biased closed by a spring |23 disposed in the valve cylinder. Cpening of the dump valve IIS is controlled by a pilot valve |25 which is operated by the armature 8l' of the trip device 8 I. When the trip device BI is energized to trip the circuit breaker the armature 81, in addition to releasing the circuit-breaker latching means, also substantially simultaneously opens the pilot valve |25 thereby establishing communication between the space oi the cylinder 29 and the top space of the dump-valve cylinder IZI above the piston-type valve H9, through a pas sage |21 (Fig. l) and a pipe |29 (Fig. 2). The pressure air in the circuit-breaker operating cylinder 29, if there is any compressed air in the cylinder at this time. is directed to the top of the piston-type dump valve l I3, and initiates opening movement of the dump valve. As soon as this dump valve is cracked open a small amount, the pressure air begins to new from the cylinder 2S through the dump ports IIE and partially-open dump valve directly to atmosphere, and the pressure of this air quickly completes the opening movement of the dump valve I|0. Pressure air in the operating cylinder 29 above the operating piston is thus very quickly dumped directly to atmosphere thereby facilitating quick reversal c! the circuit breaker and its operating piston and high speed initial opening movement thereof.

The dump ports I I5 are so located intermediate the end positions o the breaker-operating piston that they will be closed oil from the upper portion of the cylinder space by the operating piston after the circuit breaker has opened a predetermined distance sufficient to interrupt the circuit. This permits quick automatic reclosing operation of the circuit breaker to be initiated before the breaker reaches the full-open position by energizing the control-valve device Ii3 to admit compressed air to the operating cylinder before the breaker reaches full-open position.

The operating mechanism is operable tc produce normal closing opera-tion of the circuitl breaker starting from the Iull open-circuit position and is also operable to eect quick auto matic reclosing operations ol the circuit breaker wherein the reclosing movement is initiated at an intermediate point in the opening stroke of the breaker after the circuit is interrupted but before the breaker reaches the full open position, or at least by. that time. The control circuits for controlling the operation of the control electromagnet of the control valve-device ||3 and the trip device 8| may be the same as the control circuits disclosed in the aforementioned copending application Serial No. 410,686. These control circuits have not been shown in this applicationv as they are not necessary for a complete understanding ofA the present invention. It is believed sufflcient to state that the tripping electromagnet 8 is energized in response to an overload or short circuitin the main circuit and can also be energized by a manual trip-control switch. For quick automatic reclosing operations, the electromagnet which controls the inlet control-valve device ||3 is arranged to be automatically energized by an auxiliary switch at an intermediate point in the opening stroke of the breaker to cause the valve to admit compressed air to the operating cylinder at the proper time. The auxiliary switch is adjustable so that regular automatic reclosing operation from the full open position may be attained if desired. The electromagnet of the control valve-devce ||3 may also be energized by a manual closing-control switch.

- In accordance with the present invention, the operating mechanism is provided with an improved combination intake and exhaust valvedevice I3 for admitting compressed air to the operating cylinder for effecting closing of the breaker, and for also rapidly venting the cylinder directly to atmosphere to facilitate quick reversal and high-speed operation of the circuit breaker and its operating means.

The control valve-device |3 comprises a valvehousing |35 which is secured to the side ofthe main cylinder casting 21 by a plurality of bolts (not shown), a suitable sealing gasket being provided in the joint. The valve-housing has a chamber or opening |31 which communicates with the interior of the air storage-tank and an inlet-passage |39 communicating with the inlet-port 4| in the upper end of the breaker operating cylinder 29. The flanged neck of the air storage-tank is secured to the valve-house |35 by a plurality of bolts (not shown), a suitable sealing gasket being provided to make the joint air-tight. A main inlet valve-element |43 disposed in the valve-housing has a stem |45 slidably mounted in a guide sleeve |46 carried by a bushing |41. opening in the housing between chamber |31 and the inlet-passage |39 and this bushing serves as a valve-seat for the inlet valve-element |43. The

guide-sleeve |46 is connected to the-bushing byA a plurality of spider-arms which permit the compressed air to ow when the valve is open. The inlet valve-element is biased to closed position to close the inlet-passage, by a helical compression-spring |49 which surrounds the guide-sleeve,

The bushing is threaded in anl inoperative position against the head of the cylinder by means of a helical compression-spring |55 which surrounds a portion of the valve-spring and is disposed between the underside of the valvepiston |53 and a shoulder formed in the valvehousing.

The inlet valve-operating piston |53 is adapted to Vbe moved downwardly to open the main inletvalve, by compressed air from the tank through passages |51, |59 and |6| in the valvehousing. The air-passages |51 and |59 communicate with cooperating passages in a pilot valvehousing |63 which is secured to the main valvehousing |35. Communication between the airtank and the top of the valve-piston |53 is normally shut off, however, by a pilot-valve |65 disposed in the pilot valve-housing |63. The pilot-valve I 65 is biased to closed position against its seat by a compression-spring |61 and is adapted to be operated to open position to cause airpressure to open the main inlet-valve, by means of an electromagnet |1| upon energization thereof.

The control valve-device ||3 is also adapted to very rapidly vent the breaker-operating cylinder 29 directly to atmosphere when the inlet valve-element is closed in order to facilitate quick reversal of movement of the breaker and its operating piston and high-speed opening operation of the breaker retarded by back pressure in the operating cylinder. For this purpose, the control valve-device 3 is provided with a large exhaustpassage |13, at least as large in cross section as the inlet-passage |39 and inlet port |4|. The exhaust-passage |13 communicates directly with the inlet passage and inlet port, and is normally opened to atmosphere by an exhaust valve-element |15. The exhaust valve-element |15 is substantially piston shaped and of hollow construction to make it light in weight, and this valveelement is slidably mounted in a transverse opening provided in a housing |11 which is secured to the housing |35. The housing |11 may be formed integral with the housing |35 if desired. The exhaust valve-element |15 is biased to open position as shown by a helical compression-spring |19 disposed in the opening of the housing section. Inv the open position, the exhaust valveelement opens the exhaust-passage |13 to atmosphere through the exhaust-port |8|. The exhaust valve-element |15 is arranged to be pneumatically operated to closed position to close the exhaust-passage |13 upon opening of the pilotvalve |65, and for this purpose is provided with a piston-portion |83 of reduced cross-section which slides in a cylinder |85 in the housingsection |11. Upon opening of the pilot-valve |65, compressed air is admitted from the tank to the head of the exhaust valve-piston |83 through the passages |51, |59 and a passage connecting |59 to the head of the cylinder |85. The exhaust-valve |15 and the actuating piston |53 of the inlet-valve are pneumatically interlocked by the passage |6| so that upon opening' of the pilot-valve |65 closing operation of the exhaust-valve 15 will be initiated before opening of the inlet-valve |43. Compresed air is first admitted to the piston |83 of the exhaust-valve and as the exhaust-valve |15 closes, the piston |83 uncovers the passage |6| so that compressed air is then admitted to the top of the actuating piston |53 of the inlet-valve |43 to effect opening of the inlet-valve. This prevents loss of compressed air through the exhaust-passage.

The pilot-valve |65 has an exhaust-valve |81 connected thereto which closes when the pilotvalve |65 opens and opens when the pilot-valve closes to vent the valve-cylinder of the inlet valve-piston |53 and the valve-cylinder |83 to atmosphere to allow the springs to quickly close the inlet-valve |4| and open the exhaust-valve |15 upon deenergization of the pilot valve-electromagnet l1 I. The inlet-valve |43 will close slightly before opening of the exhaust-valve |15. A push button |88 is provided on the electromagnet |1| for manually operating the pilot valve to open position to effect closing of the circuit breaker.

The operation of the circuit-breaker mechanism is briefdy as follows: Assuming the circuit breaker is in the open position shown in Fig. l, closing of the circuit breaker is effected by closing a manual control-switch to effect energization of the electromagnet |1| of the control valvedevice. When the electromagnet |1| is energized, the pilot-valve |65 opens and admits compressed air from the tank to the piston |83 of the exhaust-valve 15 quickly closing the exhaustvalve. As the exhaust-valve |15 closes the piston |83 uncovers the passage IBI, thereby admitting compressed air to the actuating piston |53 to open the main inlet-valve |43. Compressed air is thereupon admitted from the tank directly to the upper end of the main operating cylinder 29 driving the operating piston |53 downwardly to the bottom of the cylinder to effect closing of the circuit breaker. As soon as the breaker reaches closed position, the electromagnet |1| is deenergized and the pilot-valve |65 closes to cause the main inlet-valve |43 to quickly close and the exhaust-valve |15 to quickly open. Opening of the exhaust-valve |15 quickly vents the cylinder 29 directly to atmosphere so that there will be substantially no back pressure to retard opening of the circuit breaker. If there is no fault condition, such as a short circuit, in the main circuit at the time the circuit is closed by the breaker, the circuit breaker will be latched closed and held closed by the latching means 5|E5. However, if an overload or short-circuit condition exists, the trip-device 8| will be energized as soon as the circuit breaker closes the circuit, Operation of the trip device causes release of the latching means 5|-E1 and simultaneous opening of the dump pilot-valve |25. Upon. opening of the pilot-valve |25, the pressure air in the operating cylinder 29 immediately opens the dump-valve ||9 quickly collapsing the air pressure in the cylinder. As a result, the movement of the circuit breaker is quickly reversed as soon as it reaches closed position and the circuit breaker opens at high speed unretarded by back pressure in the cylinder. The dump-valve ||9 opens an instant before the inlet-valve |43 closes and the exhaustvalve |15 opens, thus facilitating quick reversal and high speed initial opening of the breaker. During the first part of the opening movement, the cylinder 29 is vented both by the dump-valve I9 and the exhaust-valve |15, and during the remainder of the opening stroke after the dumping ports ||5 are closed by the piston, venting takes place through the exhaust-valve.

Assuming the circuit breaker is standing in closed position and an overload or short circuit occurs in the main circuit, the trip-device 8| will be energized causing the latching means 5|-61 to release the circuit breaker whereupon the circuit breaker is operated at high speed toward open position by its opening spring l5. Although the dump pilot-valve |25 is operated simultaneously with the release of the circuitbreaker latching means, there is no compressed air in the operating cylinder at this time since the cylinder has been vented by the exhaustvalve |15, consequently, the dump-valve H9 does not open. As the piston moves upwardly, the air above the operating piston is rapidly exhausted to atmosphere through the open exhaust-passage |13 so that high-speed opening operation of the breaker is obtained unretarded by back pressure in the cylinder 29.

If the breaker control circuit has been set for quick automatic reclosing, the electromagnet |1| will be energized at a predetermined intermediate point in the opening stroke causing compressed air to instantly close the exhaust valve |15 and open the inlet valve |43, thereby admitting compressed air to the cylinder' 29 to initiate reclosing operation of the breaker before the breaker reaches the full open position. When the breaker reaches the closed position, the electromagnet is deenergized and the inlet-valve |43 closes and the exhaust-valve |15 opens. If the fault condition is cleared by the time the breaker closes, the circuit breaker will be latched closed and held closed by the latching means 5|-B1. However, if the overload or short circuit-condition is still present at the time the circuit breaker recloses the circuit, the trip-device 8| will be again energized to cause release of the latching means 5|-51 and opening of the dump pilotvalve |25. The pressure air in the cylinder will immediately open the dump-valve ||9 and cause quick collapse of pressure in the cylinder 25. As a result, the movement of the circuit breaker will be quickly reversed and opening operation of the circuit breaker by its opening spring will take place at high speed unretarded by back pressure in the cylinder 29.

Although the dump valve ||9 and dumping ports ||5 are desirable to help provide for very high speed reversal of the circuit breaker and its operating piston and to provide very high speed initial opening movement of the breaker, they may be omitted if desired as the large exhaust passage and quick acting exhaust valve of the control valve mechanism ||3 provide for quick reversal and good high speed opening operation without the dump valve and dumping ports. The circuit breaker and operating piston can be quickly reversed and opened at high speed from any point in the closing stroke by closing of the pilot valve since the closing of the pilot valve will cause the valve device to quickly shut off the ow of compressed air to the breaker cylinder and fully and rapidly vent the cylinder directly to atmosphere.

The improved control valve device |I3 may be applied to other types of pneumatic circuit breaker operating mechanisms. In the case of a double acting pneumatic mechanism where the circuit breaker is both opened and closed by compressed gas, each end of the cylinder can be provided with the control valve device of the present invention. The control valve device disclosed can also be used with advantage in a pneumatic operating mechanism embodying a mechanically trip free linkage or lever system to permit quick reverse movement of the piston in its resetting direction to reset the trip free linkage.

The provision of the pneumatic operating mechanism with the improved control valve device disclosed provides for quick reversal of operation and high speed operation of the circuit breaker. The large exhaust passage and exhaust valve element function to rapidly vent the breaker operating cylinder directly to atmosphere when the inlet valve element closes. The device is simple and compact and the valve elements thereof respond and operate very quickly'through relatively short strokes, and only a small amount 'may be made Without departing from theessential features of the invention.

I claim as my invention:

1. In an electric circuit breaker having relatively'movable contacts, operating means therefor including a cylinder and a piston therein operatively related with the breaker for closing the breaker, a source of compressed gas, a control valve device associated with said cylinder for admitting compressed gas to said cylinder to close the breaker and for also rapidly venting said cylinder directly to atmosphere, said valve device having an inlet passage, a large exhaust passage at least as large as said inlet passage for rapidly venting said cylinder directly to atmosphere, `an inlet valve element biased to close said inlet passage, an exhaust valve element operable independently of and movable relative to said inlet valve element and biased to open said exhaust passage, actuating means operable when energized to cause quick closing of said exhaust vvalve and opening of said inlet valve to admit compressed gas to said cylinder for closing said breaker, and means for delaying Opening of the inlet valve until after closing movement of the exhaust valve is initiated.

2. In an electric circuit breaker having relatively movable contacts, operating means therefor including a cylinder and a piston therein operatively related with the breaker for closing the breaker, a source of compressed gas', a control valve device` associated with said cylinder for admitting compressed gas to said cylinder to close the breaker and for also rapidly venting said cylinder directly to atmosphere, said valve device having an inlet passage, a largeexhaust passage at least as large as said inlet passage for rapidly venting said cylinder directly to atmosphere, a pneumatically operated inlet valve element biased to close said inlet passage, an exhaust valve element movable relative to said inlet valve element and biased to open said exhaust passage, said exhaust valve element controlling the admission of compressed gas tol operate said inlet valve and actuating vmeans operable when energized to cause quick closing of said exhaust 4valve and opening of said inlet valve to ladmit compressed gas to said cylinder for closing said breaker and spring means biasing said valve elements to quickly close said inlet valve element and open said exhaust valve element upon deen- Aergization of said valve actuating means.

3. In an electric circuit breaker having relatively movable contacts, operating means therefor including a cylinder and a piston therein operatively related with the breaker, a sourcelof compressed gas, a control valve device associated With said cylinder for admitting compressed gas to said cylinder to actuate said piston 'in one direction and for also rapidly venting said cylinder directly to atmosphere to permit high speed reverse movement of said piston, said valve device having an inlet passage, a large exhaust passage, at least as large as said inlet passage for rapidly venting said cylinder directly to atmosphere, an inlet valve element operable by compressed gas and biasedto close said inlet passage, an exhaust valve element biased to open said exhaust passage and movable relative to said inlet valve element to close said exhaust passage and admit compressed gas to operate said inlet valve, actuating means operable when energized to quickly close said exhaust valve element and cause opening of said inlet valve element for effecting closing operation of the breaker, and means controlling the energization of said valve elements to initiate closing of said exhaust valve element prior to opening of said inlet valve element.

4. An operating mechanism'of the pneumatic type for an electric circuit breaker comprising a cylinder and a piston therein for operating the circuit breaker, a source of compressed gas, a control valve device associated with said cylinder arranged to admit compressed gas to said cylinder for moving said piston in one direction to operate said circuit breaker and to also rapidly vent said cylinder directly to atmosphere for permitting high speed reverse movement of said piston, said valve device having an inlet passage through which compressed gas is admitted to said cylinder, a large exhaust passage at least as large as said inlet passage for rapidly venting said cylinder directly to atmosphere, an inlet valve element biased to close said inlet passage and operable by compressed gas to open said inlet passage, an exhaust valve element operable by compressed gas mechanically independently of said inlet valve to closed position and movable relative to said inlet valve element, spring means for biasing and quickly moving said inlet valve velement to closed position and said exhaust valve element to open position, compressed gas actuating'means for quickly closing said exhaust valve element and opening said inlet valve element to admit compressed gas to said cylinden'and means for controlling the admission of compressed gas to said valve elements to initiate closing of said exhaust valve element prior to opening said inlet valve element, and an electromagnetically controlled pilot valve for admitting compressed gas to said valve actuating means.

5. An operating mechanism of the pneumatic type for an electric circuit breaker comprising a cylinder and a piston therein operatively related to the circuit breaker for operating said circuit breaker, a source of compressed gas, a control valve device associated with said cylinder for admitting compressed gas to said cylinder to move said piston in one direction and for also rapidly venting said cylinder directly to atmosphere to permit high speed reverse movement of said piston, said valve device having an inlet passage through which compressed gas is supplied to said cylinder, a large exhaust passage at least as large as said inlet passage for rapidly venting said cylinde!` directly to atmosphere, an inlet valve element biased to normally close said inlet passage and operable by compressed gas to open said inlet passage, an'exhaust valve element movable relative to said inlet valve element and biased to open said exhaust passage, spring means for biasing and quickly closing said inlet valve element, piston means operable by compressed gas to quickly close said exhaust valve element and to admit compressed gas to the inlet valve to open cally operated pilot valve for controlling the now of gas to said valve piston means.

6. A pneumatic operating mechanism for an electric circuit breaker comprising a latch for holding said circuit breaker closed, means for tripping said circuit 1breaker open, a cylinder and a piston therein for closing said circuit breaker, a source of compressed gas for operating said piston to close said circuit breaker, a control Valve device associated with said cylinder arranged to admit compressed gas to said cylinder for actuating said piston to close the breaker, and to also rapidly 'vent said cylinder directly to atmosphere tc permit high speed reverse movement of said piston, said valve device having an inlet passage for admitting gas to said cylinder, a large exhaust passage at least as large as said inlet passage for rapidly venting said cylinder directly t atmosphere, a pneumatically operable inlet valve element spring biased to close said inlet passage, an exhaust valve element operable independently of and movable relative to said inlet valve element and spring biased to open said exhaust passage, said exhaust valve having a portion for controlling the admission of compressed gas to operate said inlet valve, compressed gas actuating means operable to quickly close said exhaust valve element and open said inlet valve element to admit compressed gas to said cylinder for closing said circuit breaker, means for delaying opening of said inlet valve element until after closing movement of said exhaust valve element is initiated, and an electromagnetically controlled pilot valve operable when energized to admit compressed gas to said valve actuating means and when deenergized to vent said valve actuating means to atmosphere.

7. In an electric circuit breaker having relatively movable contacts, operating means thereor including a cylinder and a piston therein for operating the circuit breaker, a source of fluid under pressure, and a control valve device associated with said cylinder for admitting uid under pressure to said cylinder to operate said piston and for also rapidly 'venting said cylinder directly to atmosphere, said valve device having an inlet passage, a large exhaust passage at least as large as said inlet passage for rapidly venting said cylinder to atmosphere, an inlet valve element biased to close said inlet passage, an independently movable exhaust valve element biased to open said exhaust passage, said valve elements being actuated by iluid pressure, means on said exhaust valve for controlling the admission of fluid under pressure to operate said inlet valve, and an electromagnetically actuated pilot valve for admitting iiuid under pressure to actuate said exhaust valve element to closed position and to admit fluid under pressure to operate said inlet valve element to open position to thereby admit iiuid under pressure to said cylinder for operating said circuit breaker.

8. A pneumatic operating mechanism for an electric circuit breaker comprising a cylinder land a piston therein for operating said circuit breaker, a source of compressed gas, a control valve device connected to said cylinder for admitting compressed gas to said cylinder to move said piston in one direction and for also rapidly venting said cylinder directly to atmosphere to permit high speed reverse movement of said piston, said control valve device having an inlet passage through which compressed gas is admitted to said cylinder, a large exhaust passage at least as large Asaid inlet valve element, and an electromagnetias said inlet passage and communicating therewith for rapidly venting said cylinder directly to atmosphere, an inlet valve element biased to close oiT said inlet passage from said source, an exhaust valve element movable relative to and mechanically independently of said inlet valve element and biased to open said exhaust passage, spring means for quickly closing inlet valve element and for quickly opening said exhaust valve element, and compressed gas actuating means controlled by an electromagnetically operated pilot valve for quickly closing said exhaust valve element and opening said inlet valve element.

9. A pneumatic operating mechanism for an electric circuit breaker comprising a cylinder and an operating piston therein for operating said circuit breaker, a source of compressed gas, a control valve device associated with said cylinder for admitting compressed gas to said cylinder to move said piston in one direction and for also rapidly venting said cylinder directly to atmosphere to permit high speed reverse movement of said piston, said valve device having an inlet passage through which compressed gas is admitted to said cylinder, a large exhaust passage cornmunicating with said inlet passage for rapidly venting said cylinder directly to atmosphere, an intake valve element biased to close off said inlet passage from said source, an independently movable piston type exhaust valve element biased to open said exhaust passage, a piston for actuating said inlet valve to open position, and means for admitting compressed air rst to said exhaust valve element to close it and then admitting compressed air to said intake valve piston to open said intake valve.

10. A pneumatic operating mechanism for an electric circuit breaker comprising a cylinder and an operating piston therein for operating said circuit breaker, a source of compressed gas, a control valve device associated with said cylinder for admitting compressed gas to said cylinder to move said piston in one direction for operating the circuit breaker and for also rapidly venting said cylinder directly to atmosphere to permit high speed reverse movement of said piston, said valve device having an inlet passage through which Vcompressed gas is admitted to said cylinder, an inlet valve biased to close said passage and having a piston means actuated by compressed gas to open said inlet valve, a large exhaust passage for rapidly venting said cylinder directly to atmosphere, an exhaust valve mounted for movement independently of said inlet valve and biased to open said `exhaust passage, said exhaust valve having piston means actuated by compressed gas to open said exhaust valve, means including an electromagnetcally actuated pilot valve for admitting compressed gas to said exhaust valve piston means to close said exhaust valve, and a passage uncovered upon closing movement ci said exhaust valve for admitting compressed gas to said inlet valve piston means to open said inlet valve.

11. In an electric circuit breaker having relatively movable contacts, operating means therefor including a cylinder and a piston operatively related with the movable contact, a source of fluid under pressure, a control valve device associated with said cylinder having a normally closed inlet passage operable to admit fluid under pressure to said cylinder for closing said circuit breaker and having a normally open large exhaust passage at least as large as said inlet passage, closed when said inlet passage is open and open when assaaas f 7 said inlet passage is closed for rapidly exhausting said cylinder directly to atmosphere, a latch for holding said circuit breaker closed, said cylinder having a large fluid dumping port intermediate the end positions of said piston, a dump valve normally closing said dumping port operable to open position for instantaneously exhausting said cylinder to atmosphere to permit 'high speed initial opening movement of said piston, and

means for releasing said latch and for substantially simultaneously controlling operation of said dump valve, said piston closing off said dumping port from the cylinder space 0n the working side of said piston after it passes an intermediate point in its opening stroke so that iiuid under pressure can be admitted to said cylinder to quickly reclose the circuit breaker.

JAMES M. CUMMING.