US2773484A

US2773484A - Pneumatically operated circuit breaker with closing valve cutoff switch

Info

Publication number: US2773484A
Application number: US328215A
Authority: US
Inventors: Henry L Peek
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1952-12-27
Filing date: 1952-12-27
Publication date: 1956-12-11
Anticipated expiration: 1973-12-11

Description

Dec., M, E956 H. L. PEEK 297273,44

PNEUMATICALLY OPERATED CIRCUIT BREAKER WITH CLOSING VALVE cUToFF SWITCH Filed Dec. 27, 1952 @MMF/ZM v f" United States Patent PNEUMATICALLY OPERATED CIRCUIT BREAKER WITH CLOSlNG VALVE CUTOFF SWITCH Henry L. Peek, Boston, Mass., assigner to Aliis-Chalmers Manufacturing Company, Milwaukee, Wis.

Application December 27, 1952, Serial No. 328,215

13 Claims. (Cl. 121-38) This invention relates to circuit breakers and more particularly to pneumatically operated high speed circuit breakers.

One of the problems existing in the prior art which limited the speed of operation of a pneumatically operated circuit breaker was the excessive time needed to reclose the circuit breaker contacts. Pneumatic operators of the cylinder and piston type have been provided with dumping means for causing quick collapse of gas pressure in front of the piston to permit rapid piston reversal action. However, the high speed repetitive reclosing duty cycle operation demanded of power circuit breakers, which are pneumatically operated, was not fullled by the dumping means known.

In order to accomplish the extremely high speed reclosing duty cycles demanded with pneumatically operated power circuit breakers, it is necessary to deenergize a solenoid gas inlet valve, used to actuate the circuit breaker contact closing motor, very quickly after the closing stroke of the circuit breaker is completed. By deenergizing and, in turn, closing the solenoid gas inlet valve at a predetermined time, only enough gas is admitted to the contact actuating motor to close the circuit breaker contacts. A

, quick deenergization of the gas inlet valve reduces the gas consumption per operation and thereby increasesthe number of stored operations that can be obtained from a given gas storage tank.

High speed reclosing circuit breaker action is provided by a mechanism comprising a pneumatic operator employing a cylinder and a contact actuating piston, a solenoid operated gas inlet valve, and a pneumatically operated gas blast cutoff switch. As the contact actuating piston nears the end of its stroke in contact closing direction, a port is uncovered in the side of the cylinder wall of the operator which admits gas to act on a piston of the gas blast cutol switch. The piston of the cutoi switch moves under the influence of the gas being vented from the circuit breaker pneumatic operator to interrupt the electric circuit to the solenoid operated gas inlet valve. An antipumping feature is added to the cutoff switch by providing a holding coil which is not able to actuate the movable contact of the cutoi switch when the switch is closed because of the initially long air gap, but which is capable of holding the cutoi switch open once it is opened by gas under pressure. The cutoif switch with the antipumping feature will not reclose and allow another separation of the circuit breaker until a control circuit is deenergized.

It is, therefore, one object of the present invention to provide a new and improved pneumatic circuit breaker operating system capable of eilecting high speed opening and reclosing of the circuit breaker contacts.

Another object of this invention is to provide a new and improved pneumatic circuit breaker operating mechanism of the cylinder piston type in which only enough gas under pressure is allowed in the cylinder of the operating mechanism to reclose the circuit breaker contacts.

A further object of this invention is to provide a new vand improved pneumatic circuit breaker operating mecha- 2,773,484 Patented Dec. 11, 1956 nism in which gas that has been used to close the circuit breaker contacts is used to interrupt further gas ow to the pneumatic operator.

A still further object of this invention is to provide a new and improved pneumatic circuit breaker operating mechanism in which the act of dumping of exhaust gases from the pneumatic operator also interrupts current flow to the solenoid gas inlet valve controlling the pneumatic operator.

A still further object of this invention is to provide a new and improved circuit breaker operating mechanism in which circuit breaker control is obtained with a minimum of parts.

Other objects and advantages of the invention will become apparent from the following description when read in connection with the accompanying drawing, in which:

Fig. 1 is a View, partly in section, of a pneumatic circuit breaker operating system embodying the present invention;

Fig. 2 is an enlarged View taken on line lI--II of the electromagnetic gas blast cutoff switch of Fig. l looking in the direction of the arrows; and

Fig. 3 is an enlarged view taken on line III--III of the electromagnetic gas blast cutoff switch of Fig. 1 looking in the direction of the arrows.

Referring more particularly to the drawing by characters of reference, Figs. l, 2 and 3 illustrate a pneumatic motor 1 of the cylinder and piston type operatively connected by a linkage 2 of the trip free type to a circuit breaker 3.

As diagrammatically shown, the circuit breaker 3 comprises a pair of stationary Contact members 4 and a movable contact member 5. The circuit breaker is biased to open circuit position by means of accelerating spring 6. The movable contact member 5 is supported by a breaker rod 7 which, in turn, is supported by lever 8 pivoted at 9. Lever 8 is connected to bell crank 10 by means of operating rod 11. Bell crank 10 is pivoted at 57 and forms part of linkage 2.

Motor 1 comprises a main casting 12 defining the lateral wall of the operating cylinder of the motor, a top element 13 and a base element 14. Piston 15 of motor 1 is biased in the downward direction by any suitable means such as a helical spring 16 of which one end rests against top element 13 while its other end rests against piston 15. Base element 14 defines a passage 83 which is connected to duct 17 for admitting gas under pressure from a suitable source (not shown) to the cylinder of motor 1. The flow of gas under pressure from the source to the cylinder of motor 1 is controlled by a solenoid operated valve 90. Upon admission of gas under pressure to motor 1, piston 15 is moved upward against the bias of spring 16. Piston 15 is provided with a ram 18 adapted to cooperate with a roller 19 forming part of linkage 2. Upon raising of piston 15, the parts by which linkage 2 is constituted are moved to their position shown in Fig. 1, which causes engagement of contacts 4 and 5 of circuit breaker 3. Linkage 2 is then latched in by latching means which are fully described below, and thus linkage 2 restrains circuit breaker 3 in the closed position thereof against the bias of accelerating spring 6. When circuit breaker 3 is closed, piston 15 and ram 18 are free to move to their initial position shown in Fig. l under the combined action of gravity and spring 16.

Linkage 2 includes a bell crank 20 pivoted at 21 and connected by pin 22 to toggle link 23, Crank 20 and toggle link 23 form a toggle Ztl, 23 which is slightly olf center in the closed position of the breaker as shown in Fig. l and which may be caused to collapse. The center pin 22 of toggle 2t), 23 supports the above referred to roller 19 adapted to be acted upon by the ram 18 on piston 15. The right end of link 23, as viewed in Fig'l,

is pivoted at 24 on a floating lever 25. Link 26 interconnects floating lever 25 and bell crank 10. The main latch 27 is pivotally supported at 23 by stationary bracket 29 and acted upon by compression spring 30 of which one end bears against the main latchl 27, while the other end bears against bracket 29. The lower end of main latch -27 is adapted to engage a latch plate 31 forming an integral part of bell crank 2Q. The upper end of main latch 27 constitutes an abutment 32 adapted to be engaged by a cooperating abutment 33 on latch 34. Latch 34 is pivoted at 35 and acted upon by a compression spring 36 tending to pivot it clockwise about pin 35. As viewed in Fig. l, the right side of latch 34 is provided with a cam surface 37 adapted to engage a roller 38 carried by oating lever 25 by means of'pin 39. Upon release of roller 38 by cam surface 37, floating lever 25 is free to move yunder the action of accelerating spring 6, and this permits separation of contacts 4 and 5 of circuit breaker 3. When roller 38 has been released by cam surface 37, pin 39 moves from left to right along a substantially straight path detined by guiding means 40. Latch 34 is also provided with a straight cam surface 54 adapted to engage roller 33 during the interrupting process of the circuit breaker, as will more clearly be seen as the description progresses. An upper cam surface 41 on latch 34 rests against a latch 42 pivoted at 43 and acted upon by compression spring 44 tending to pivot it clockwise about pin 43. Latch 42 is held in position by a latch 45 engaging pin 46 on latch 42. Latch 45 is pivoted at 47 and biased counterclockwise by spring 48. The left arm of latch 45 is adapted to be pulled upward by a solenoid 49, thus causing latch 45 to pivot clockwise about pin 47. Lever 50 is pivotally mounted on pin 51 and adapted to engage lever 52 which is pivotally mounted on pin 53. Lever 52 is spring biased clockwise. Upon pivoting of lever 50 clockwise about pin 51 which may be eifected manually), lever 52 is pivoted against the action of its biasing spring counterclockwise about pin 53. This causes latch 45 to be pivoted in a clockwise direction about pin 47, releasing latch 42. Latch 42 then pivots counterclockwise about pin 43 which releases latch 34 and roller 33 on floating lever 25 which, in turn, initiates separation of contacts 4 and 5 under the action of accelerating spring 6.

The separation of contacts 4, may 4be initiated and effected in a vsimilar way by energizing the solenoid 49 in response to the occurrence of a fault in the system into which the breaker is connected or in response to manual operation of an auxiliary switch.

A resetting compression spring 55 is arranged below the linkage and -latch system 2 of the breaker and biases bell crank 2t) clockwise. When the breaker is tripped the linkage and latch system 2 will be reset by the action of spring 55.

To close the breaker, compressed gas is admitted to ltluid motor 1 through duct 17 and passage 83, thus causing piston 15 vand ram 18 to move upward. The closing force of motor 1 is applied to linkage 2 by engagement of ram 18 and roller 19. Toggle 2t), 23, in moving up during a closing stro-ke of piston 15, rotates floating lever 25 counterclockwise about pin 39. That rotary motion of lever 25 causes link 26 to be moved to the right. This, in turn, causes bell crank to rotate clockwise about pin 57, pulling connecting rod 11 down and breaker rod 7 up, thereby closing the breaker against the action of accelerating vspring 6.

As mentioned above, tripping may be initiated either mechanically by lifting the lleft end of lever 5t), or electrically by energizing trip solenoid 49. ln both instances the ensuing sequence of operation is about the same. When trip solenoid 49 is energized the armature thereof lifts latch 45 against the bias of spring 48. The resulting clockwise rotation of latch 45 about pivot 47 releases pin k46'on latch 42. rlhus llatch 42 is free to rotate counter'clockwise under the action of breaker accelerating spring 6 transmitted through cam surface 41 and against the bias of spring 44, thereby sliding olf the large latch 34. The large latch 34 is then free to rotate counterclockwise about pin 35 under the action of roller 38 which is acted upon by accelerating spring 6. The counterclockwise rotation of latch 34 against the bias of spring 36 permits the top end of floating lever 25 to move to the right. As pin 39 on lever 25 moves to the right it slides in guiding means 40. That movement of lever 25 and pin 39 permits parts 7, 8 and 11 of breaker 3 to move to open circuit position.

Counterclockwise rotation of latch 34 about pin 35 causes abutment 33 to engage abutment 32 on main latch 27, thereby rotating main latch 27 clockwise about pin 28. Thus, main latch 27 becomes disengaged from latch plate 31 on bell crank 2t).

Assuming now that there is a main latch failure, i. e., that either the main latch 27 or the latch plate 31 are so badly damaged (either broken or worn out) that-they fail to restrain the breaker in closed circuit position, the breaker will then reopen under the action of accelerating spring 6, but its opening movement might be relatively slow on account of the decelerating action, or dash'pot action, of Huid motor 1. Even if the supply of cornpressed gas is shut olf from motor 1 and the lower side of the motor 1 is being vented to atmosphere by prior art venting means, the decelerating etfect of motor 1 might be too large and the speed of separation of the contacts 4, 5 too small to achieve a safe interruption of the circuit controlled by the breaker. The dumping means shown in Fig. l are, however, so effective as to preclude any danger in case of complete failure of latching means 27 and 31.

As shown in Fig. l, dumping of gas under pressure previously admitted through passages 17 and 83 to cylinder 12 may be effected by a piston type valve which has been generally indicated by reference character v58. Dump valve 5S comprises a cylindrical valve body 59 and a valve element 60. Valve element 60 is movably arranged within valve body 59 and biased to closed position by means of helical spring 61. Valve element 60 is in the shape of a piston and one end of spring 61 rests against the inner side thereof, while the other vend of spring 61 rests upon the base of valve body 59. Valve body 59 is provided with an intake 62. and an exhaust opening 63. Dumping tube 64 interconnects the base `14 of motor 1 withintake opening 62 of valve 58. The top of valve body 59 is provided with a screw threaded opening 65. Cylinder 12 of motor 1 is provided with an orice 66 which is uncovered toward the end of 'each closing stroke of piston 15 so as to permit passage of compressed gas previously admitted to motor 1 through passage 17. Permanently open duct 67 interconnects 'orice 66 with pilot opening 65.

Upon uncovering of orifice 66 by piston 15 compressed gas owing through `duct 67 depresses valve element '60 against the bias of spring 61. This etfects initial opening of valve 53, permitting compressed gas from motor 1 to enter through intake opening 62 into the body'59 of valve 58, tending to push valve element 66 farther down to uncover exhaust port 63. Upon uncovering of port 63, gas under pressure below piston 15 is free to flow through passage 64, intake opening 62, the space within valve 58 above valve element 60 and exhaust opening 463 to atmosphere.

When valve 58 has been wide opened by compressed gas admitted to it through passage 64, a high pressure zone forms on top of valve element 60 tending to maintain valve element 60 in its open position against the bias of spring 61. Thus, valve element 60 remains safely open when, as a consequence of the reversal of the movement of piston 15 'under the action of spring 16, orifice 66 in cylinder 12 is reclosed or obstructed by piston 15 as it moves downward. ln the position of valve 53 shown in Fig. l, valve element 66 shutsorf intake opening 62 from the inside of valve body 59 and, as long as this is the case, valve 58 cannot be opened by any pressure of gas in passage 64.

Cracking of valve 58 by compressed gas supplied through duct 67 and pilot port 65 to the top of valve element 60 occurs close to the end of each closing stroke of piston 15. There must be sufiicient power behind piston to insure engagement of main latch 27 and latch plate 31 before compressed gas can be dumped from fluid motor 1. The moment the breaker 3 is restrained in closed circuit position by engagement of latching means 27 and 31, any gas under pressure Within the cylinder 12. of motor 1 can instantly completely be dumped. lf the latch mechanism 27, 31 performs properly upon closing of circuit breaker 3 by fluid operated motor 1, the circuit breaker remains in closed circuit position (unless it should be tripped at that time either manually or automatically) but dumping of gas under pressure through passage 64, intake port 62, valve 58 and exhaust port 63 nevertheless occurs and results in substantially `instantaneous high speed reversal of the movement of piston 15 to its position shown in Fig. 1. Piston 15, upon having reached that position, is ready to perform another closing operation.

In order not to decelerate the closing stroke of piston 15 by formation of a cushion of compressed air in front of it, the top end of iiuid motor 1 is permanently vented to atmosphere by provision of one or more venting holes 13a in cover casting 13.

The biasing action of spring 61 is extremely light. Therefore valve 58 remains open as long as there is but a small amount of pressure in the lower portion of cylinder 12 in excess of atmospheric pressure.

The solenoid valve 90 which controls the gas supply to motor 1 comprises a housing 91, a valve body 92 which is biased to valve closed position by a spring 93 and a coil 94. Coil 94 is connected in series with a source of power 95, a control switch 96 and a pneumatically operated gas blast cutoff switch 97.

The cutoliE switch 97 comprises two stationary contacts 98 which are bridged by a hollow cylindrical movable contact 99. Contact 99 is secured to a piston 100 which is mounted in a cylinder 101. Cylinder 101 forms a part of an insulating housing 102. Housing 102 is provided with an inlet port 103 connected to an orifice 104 in cylinder 12 of motor 1 by means of a duct 105.

Housing 102 is fastened to a frame 106 of an electromagnet 114 by means of bolts 107. The gas inlet end of cylinder 101 in housing 102 is controlled by

contacts

98 and 99. Gas under pressure passing through duct 105 from motor 1 enters gas inlet port 103 and into the hollow cylindrical Contact 99. Contact 99 is provided with a pair of slits or openings 108 which communicate with the upstream side of piston 100. Gas from motor 1 thus passes through slits 108 to the upstream side of piston 100 to actuate piston 100 to separate the

contacts

98 and 99. Piston 100 and contact 99 are integrated into one structural unit which is biased into contact closed position by a spring 109. Housing 102 is provided with vent openings 110 which connect the downstream end of cylinder 101 with the atmosphere. Normally, the vent openings 110 are closed by piston 100 when the

contacts

98 and 99 are engaged. These vent openings are opened substantially at the same time at which contact 99 separates from contacts 98. Two arc extinguishing cross blasts are formed substantially at the time of arc initiation between

contacts

98 and 99, one at each of the two serially related breaks of the cutoff switch 97.

The electromagnet 114 comprises core structure 115, an armature 116 and a coil 117. Armature 116 forms an integral part of piston 100 and is arranged to provide with the core structure 115 a gap 118 therebetween sufiiciently large to preclude lifting of the

unit

99, 100 and 116 by the action of the coil 117. Coil 117, however,

locks unit

99, 100 and 116 in the raised position against core structure 115 once the unit has been raised by the action of compressed gas acting on the upstream side of piston 100 to thereby lock the electric circuit of coil 94 of the solenoid valve open. Electromagnet 114 provides an antipumping feature which prevents repeated attempts of the circuit breaker to close in case of a latch failure and to prevent repeated operations of motor 1 even though the circuit breaker stays closed on first closure.

Upon closing of the switch 96, both the coil 117 of the electromagnet 114 and the coil 94 of the solenoid valve 90 are energized. Coil 94 of valve 90 is energized through

contacts

98, 99 of the cutoff switch 97. Energization of the coil 94 of the solenoid valve 90 causes closing of the circuit breaker contacts 4, 5 as explained heretofore. At a predetermined position of the piston 15 of motor 1 compressed gas is admitted to the cutoff switch 97 through orifice 104 of cylinder 12, duct 105, inlet port 103 of housing 102, openings 108 of contact 99 to the upstream side of piston 100. Movement of piston upward causes interruption of the current flow in the circuit energizing coil 94 of valve 90. Deenergization of coil 94 causes closing of valve 90 and the cutoff of air to motor 1.

The conventional method employed on the type of linkage mechanism shown at 2 prior to this invention performed the air cutoff and antipumping functions with the usuall aa and "bb switches mechanically operated by shaft 21 and a Y switch. The switch 97 improves the performance of this type of prior art circuit breaker control mechanism by reducing the number of component parts, simplifying the wiring of the control mechanism, shortening the time required for opening the electric circuit of coil 94 of valve 90 after a circuit breaker operation by separating

contacts

98, 99 faster than they could have been separated mechanically, and shortening the resulting arcing time of

contacts

98, 99 by the use of fluid under pressure. The high speed contact actuation and separation of

contacts

98, 99 and the high speed arc extinction at

contacts

98, 99 make possible the ultra high speed reclosing operations of this type of circuit breaker control mechanism. The high speed action of this control switch 97 may be utilized in other forms of control mechanisms not shown or described herein.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

l. In an operating mechanism for circuit breakers, a motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a source of gas under pressure, means for admitting gas under pressure from said source to said cylinder to close the breaker, means for controlling said gas admitting means comprising a gas blast cutoff switch actuated by gas under pressure from said cylinder passing through said switch, a spring for returning said piston to the initial position thereof upon closing of the breaker, a ram on said piston for reclosing the breaker, means for venting said cylinder to cause said spring to rapidly return said piston to said initial position thereof, said venting means including a piston type valve, resilient means for biasing said valve to closed position, pilot means for cracking said valve including means defining an orifice in said cylinder controlled by said piston and means defining a permanently open duct for connecting said orifice to said Valve, and means defining a passage to atmosphere forming an integral part of said valve for maintaining said valve in open position by the action of ,gas under pressure being vented through said passage, the llast said "niea'nsb'eingoperativeonly upon crackingof said valve '-'by 'said pilot" means.

2. In an'operating mechanism for circuit breakers, a ymotor'o'perable bygas under'pressure and comprising a cylinderianda piston movably arranged therein, a source ofu'gas under pressure, means for admitting gas under pressure lfrom said source to said cylinder to close the breakenmeans for controlling said gas admitting means comprising av gas'blast cutoii switch actuated by gas under pressure from said cylinder passing through said switch, said gas being vented from said cylinder to said switch fonly upon a predetermined travel of said piston in breaker closing direction, a spring for returning said piston to the initial position thereof upon closing of `the breaker, a ram on said piston separate from said linkage and cooperating therewith after collapse thereof 'for reclosing the breaker, means for venting said cylinder to cause said spring to rapidly return said piston to said 'initial position thereof, said venting means includling a piston type valve, resilient means for biasing said valve to closed position, pilot means for cracking said valve including means defining an oritice in said cylinder controlled by said piston and means defining a permanently open duct for connecting said orice to said valve, and means defining a passage to atmosphere forming an integral part of said valve for maintaining said valve in open position by the action of gas under pressure being vented through said passage, the last said means being operative only upon cracking of said valve by said pilot means.

3. In an operating mechanism for circuit breakers, a motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a source of gas under pressure, means for admitting gas under pressure from said source to said cylinder to close the breaker, means for controlling said gas admitting means comprising a gas blast cutoff switch actuated by the action of gas under pressure being vented from said cylinder through said switch, said gas being vented from said cylinder to said switch only upon a predetermined travel of said piston in breaker closing direction, a spring for returning said piston to the initial position thereof upon closing of the breaker, a ram on said piston separate from said linkage and cooperating therewith after collapse thereof for reclosing the breaker, means for venting said cylinder to cause said spring to rapidly rcturn said piston to said initial position thereof, said venting means including a piston type valve, resilient means for biasing said valve to closed position, pilot means for cracking said valve including means defining an orifice in said cylinder controlled by said piston and means deining a permanently open duct for connecting said orifice to said valve, and means defining a passage to atmosphere forming an integral part of said valve for maintaining said valve in open position by the action of gas under pressure being vented through said passage, the last said means being operative only upon cracking of said valve by said pilot means.

4. In an operating mechanism for circuit breakers, a

`'motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a source of gas under pressure, a valve and an actuating solenoid therefor for admitting gas under pressure from said source to said cylinder to close the breaker, means for energizing said solenoid to open said valve to admit gas to said cylinder, a gas blast cutoff switch for deenergizing said solenoid to close said valve, said gas blast cutoff switch being actuated by gas under pressure passing through said cylinder to said cutoff switch after a predetermined travel of said piston in breaker closing direction, a spring for returning said piston to the initial position thereof upon closing of the breaker, a ram on said piston for reclosing the breaker, means for ventcause said spring to rapidly return ingrsaid cylinder to initial position thereof, said venting said piston to said means including a piston type valve, resilient means for biasing said piston type valve to closed position, pilot means for cracking said piston type valve including means defining an orifice in said cylinder controlled by `said piston and means deiining a permanently open duct for connecting said orifice to said piston type valve, and means defining a passage to atmosphere forming an integral part of said piston type valve for maintaining said valve in open position by the action of gas under pressure being vented through said passage, the last .i means being operative only upon cracking of said piston type valve by said pilot means.

5. in an operating mechanism for circuit breakers. a motor operable by gas under pressure and comprising a cylinder and piston movably arranged therein, a source ot gas under pressure, a valve and an actuating solenoid therefor for admitting gas under pressure from said source to said cylinder to close the breaker, means for energizing said solenoid to open said valve to admit gas to said cylinder, a gas blast cutotl switch being actuated by gas under pressure from said cylinder to deenergize said Valve comprising a pair of arcing' contacts, means for separating said contacts and yfor extinguishing the arc drawn therebetween comprising an orifice in said cylinder controlled by said piston, means defining a permanently open duct for connecting said oritice to said cutoff switch, a spring for returning said piston to the initial position thereof upon closing of the breaker, a ram on said piston for reclosing the breaker, means for venting said cylinder to cause said spring to rapidly return said piston to said initial position thereof, said venting means including a piston type valve, resilient means for biasing said piston type valve to closed position, pilot means for cracking said piston type valve including means deiining an orifice in said cylinder controlled by said piston and means defining a permanently open duct for connecting said orifice to said piston type valve, and means defining a passage to atmosphere forming an integral part of said piston type valve for maintaining said valve in open position by the action of gas under pressure being vented through said passage, the last said means being operative only upon cracking of said piston type valve by said pilot means.

6. in an operating mechanism for circuit breakers, a motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a source of `gas under pressure, electrically operated valve means for admitting gas under pressure from said source to said cylinder to close the breaker, and a gas blast cutoff switch for controlling the deenergization of said valve means comprising a pair of arcing contacts actuated by gas under pressure from said cylinder passing through said switch.

7. yln an operating mechanism for circuit breakers, a motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a source of gas under pressure, a solenoid operated valve for admitting gas under pressure from said source to said cylinder to close the breaker, and a gas blast cutoff switch for controlling the deenergization of said valve comprising a pair of arcing contacts actuated by gas being vented from said cylinder `to said switch upon a predetermined travel of said piston in breaker closing direction.

8. In an operating mechanism for circuit breakers, a motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a source of gas under pressure, a solenoid operated valve for admitting gas under pressure from said source to said cylinder to close the breaker, a gas blast cuto switch comprising :a pair of arcing contacts actuated by gas being vented 'through said cylinder to said switch to deenergize said valve, and electromagnetic means for locking said switch contacts open and said soienoid valve closed.

9. in an operating mechanism for circuit breakers. a motor operable by gas under pressure and comprising a cyinder and a piston movabiy arranged therein, a source of gas under pressure, a solenoid operated valve for admitting gas under pressure from said source to said cylinder to close the breaker, a gas blast cutol switch comprising a pair of arcing contacts actuated by gas being vented through said cylinder to said switch to deenergize said valve, and electromagnetic means for locking said switch contacts open and said solenoid valve closed, said contacts of said switch being rapidly separated and the arc drawn. therebetween being rapidly extinguished to provide for ultra high speed control of said valve.

l0. in an operating mechanism for circuit breakers, motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a source ot' gas under pressure, a solenoid operated valve comprising a coil for admitting gas under pressure from said source to said cylinder to close the breaker, an electric control circuit for said coil, a gas blast cutcfin switch comprising a pair of arcing contacts actuated by gas being vented through said cylinder to said switch to interrupt said circuit and deenergize said valve, and electromagnetic means for locking said switch contacts open and said circuit open.

ll. In an operating mechanism for circuit breakers, a motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a source of gas under pressure, a solenoid operated valve comprising a coil for admitting gas under pressure from said source to said cylinder to close the breaker, an electric control circuit t'or said coil, a gas blast cutot switch comprising a pair of arcing contacts actuated by gas being vented through said cylinder to said switch to interrupt said circuit and deenergize said valve and electromagnetic means responsive to separation of said switch contacts for locking said switch contacts open and said circuit open.

l2. in an operating mechanism for circuit breakers, a

motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a ram on said piston for reclosing the breaker, a source of gas under pressure, a solenoid operated valve for admitting gas under pressure from said source to said cylinder to close the breaker, and means for controlling the deertergization of said valve comprising a gas blast cutoff switch actuated by gas being vented from said cylinder to said switch upon a predetermined travel of said piston in breaker closing direction.

13. In an operating mechanism for circuit breakers, a motor operable by gas under pressure and comprising a cylinder and a piston movably arranged therein, a ram on said piston for reclcsing the breaker, a source of gas under pressure, solenoid operated valve means for admitting gas under pressure from said source to said cylinder to close the breaker, means for energizing said valve to admit gas to said cylinder, and means for deenergizing said valve upon a predetermined travel of said piston in breaker closing direction `and for locking said valve closed, said deenergizing means comprising a gas blast cutoff switch actuated by gas being vented from said cylinder to said switch to interrupt the electric circuit which energizes said solenoid valve and an electromagnetic means for magnetically locking said switch contacts open and said solenoid valve closed.

References Cited in the le of this patent UNITED STATES PATENTS