US2644876A - High-speed compressed-air circuit breaker - Google Patents

Description

y 7, .53 B. P. BAKER 2,644,876

meas ssn COMPRESSED AIR. cmcuxpaawsa Filed Aug. 19. 1950 WITNESSES: INVENTOR Benjamin P. Baker.

ATTORNEY Patented July 7, 1953 HIGH-SPEED COMPRESSED-AIR CIRCUIT BREAKER Q Benjamin F. Baker, Turtle Creek, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 19, 1950, Serial No. 180,447

20 Claims.

My invention relates to high-speed compressed-air circuit-breaker assemblies of either the single-action type or of the multiple-action or recloser type. My invention also relates to features which are useful in recloser types of compressed-air breakers, whether the operation is at extremely high speeds or not.

The general concept and specific embodiment of my present invention is an improvement over the breaker-assembly which is the subject of a copending application of Howard M. Wilcox and myself, Serial No. 73,516, filed January 29, 1949, in which the air-blast interrupter-assembly was mounted on the top of an insulating blast-tube which extended up from a compressed-air tank which was located at groundpotential. In such a device, a large volume of high-pressure air was trapped in the long insulating blast-tube, which had to have a substantial length, sutficient to provide the necessary insulating-distance for withstanding a substantial elevated line-potential. This large volume of high-pressure air, filling the long insulating blast-tube of said prior device, delayed both the opening action and the reclosing action of the blast-responsive contacts, because of the time necessary to bring the blast-tube air up to pressure in the first place, and to exhaust it in the second place.

The type of air-blast breaker to which my present invention is more particularly directed uses a substantially closed exhaust-chamber which has a volume designed so that it will reach about half of the air-pressure of the applied air-blast in about the time necessary for the arcinterrupting contacts to open far enough to extinguish the arc, as described and claimed in a copending application of Frisch, Aspey, Mac- Neill and myself, Serial No. 74,406, filed February 3, 1949, now U. S. Patent 2,627,005, issued January 27, 1953. This is usually quite a desirable feature of construction, particularly in air-blast breakers of any substantial high-voltage or highcurrent rating, as it maintains a pressurized area at the arc-interrupting gap, thus mate rially increasing the breakdown-voltage of the gap, and enabling a small, short-stroke gapdevice to handle millions of kilovolt-amperes, thus not only reducing the size and, therefore, the cost of the breaker, but also reducin the time of operation, because of the shortened stroke.

It is an object of my present invention to retain the advantages and to overcome the aboveindicated disadvantages of both of t ese P vious types of air-blast breakers. The disadvantage of a long insulating blast-tube is avoided, in my invention, by mounting the compressed-air tank on the top of the necessary insulating support, so that the tank is at the same electrical potential as'the arc-interrupting parts, and thus the blast-tube may be made of metal and may be extremely short.

I retain the advantage of a substantially enclosed exhaust-chamber, while still permitting fast reclosure, by adding suitable means, as will be described, for dumping the air out of the exhaust-chamber as soon as the fault-current is interruptedby the operation of the arcing contacts, this dumping operation being performed without waiting for an operation of the serialll connected isolating switch which is used with such air-blast breakers. Then, if the fault still persists, the blast-operation will be repeated, and the dump-valve on the exhaust-chamber will be reclosed.

In accordance with my present invention, I also retain, with modifications, the essential advantages of a known operating-mechanism for the isolating-switch. As shown and described in the aforesaid copending application of Wilcox and myself, Serial No. 73,516, filed January 29, 194.9,this known isolating-switch mechanism was triggered oil by an air-pressure derived from the lower end of the long insulating blast-tube of the previous construction. In my present invention, I derive this initiating air-pressure from my short blast-tube which is at a considerable height above the ground-level of the operating-mechanism, and I use an insulating duct which, by reason of its length, introduces a desirable time-delay element. The lastnamed copending application also shows an interlocking means, responsive to the opening of the isolating switch, for reclosing the blastvalve. I retain this feature, with modifications adapting it to recloser-breakers.

With the foregonig and other objects in view, my invention consists in the combinations, as-

- semblies, systems, structures, parts and methods of design and operation, hereinafter described and claimed, and illustrated in the accompanying drawing, the single figure of which is a side elevational view, partly in section, and largely diagrammatic, not to scale, indicating the general principles of my invention.

The drawing shows a single pole of a compressed-air breaker-assembly embodying my invention. It is to be understood, however, that my invention is often or usually applied to a threephase power-system (not shown), in which case each pole would consist of the structure as shown, except that a single operating-mechanism may be used for the gang-operation of the isolatingswitches of all three poles.

My illustrated compressed-air circuit-breaker assembly comprises an air-blast interrupterassembly I, mounted on the top of an insulating supporting-means 2, which stands high enough to provide a sufficient insulating-distance from a substantial elevated line-potential to ground.

In the drawing, I have illustrated a singlecolumn interrupter-assembly I, comprising two vertically aligned, self-opening, longitudinalblast main interrupter-gap devices 3 and 4. In accordance with my present invention, the bottom gap-device 3 is mounted directly on top of a compressed-air tank 5, in which air is maintained under a suitable pressure, such as 250 pounds per square inch, by any suitable compressed-air supply-means, represented by a downwardly extending insulating air-supply tube 6. The gap-devices 3 and 4 are electrically connected in series, so that the current-flow, in the normal closed position of the breaker, is from the line Li to the top 1 of the interrupterassembly I, thence through the two gap-devices 4 and 3 to the bottom I of the interrupterassembly I.

Each interrupter-gap device 3 or 4 comprises a stationary contact-member 3S or 48, a the case may be, and a vertically movable contact member 3M or 4M, respectively. The two movable contact-members 3M and AM are normally biased towards their closed poistions by means of biasing springs 33 and 4B, respectively.

In the construction which is very much preferred, the stationary contact-member 38 of the lower gap-device 3 is integrally or electrically united, at its lower end, with a substantially closed lower exhaust-chamber 3E, which i made of metal. The lower stationary contact-member BS is hollow, and extends down into the lower exhaust-chamber 3E, as shown at 3. The top end of the lower stationary contact-member 38 is provided with an orifice 3-0 which is normally closed by the abutment of the movable contactmember 3M thereagainst, in the normal closed position of the breaker.

The two movable contact-members 3M and AM are mounted within a metallic moving-contact assembly or housing I, which is in the form of two concentric cylinders, namely an inner cylinder 1i and an outer cylinder To, so as to provide an annular space is between these cylinders, through which the air-blast may pass. The moving-contact housing I is disposed between the two stationary-contact assemblies 3S and 4S, being held in place by means of two insulating tubes 3-I and 4-1 respectively. The lower insulating tube 3-]: abuts against the lower exhaustchamber 3E and supports the outer cylinder 10 of the moving-contact housing I. This lower insulating tube 3-1 is larger than the lower stationary contact-member 3S, so as to provide an annular space 35 therearound, through which the air-blast may pass, as will be subsequently described.

It is an important feature of my present invention that I provide the shortest possible blasttube 8 for, at times, supplying a blast of air from the compressed-air tank 5 to the bottom of the annular space 33 of the bottom gap-device 3. This blast-tube 8 is shown as comprising a funnellike air-guiding duct which is integral with the lower exhaust-chamber 3E, and which extends vertically all the way through said exhaustchamber The small lower end of the funnellike blast-tube 3 is in hermetically tight communication with the compressed-air tank 5, and this communication is normally closed by means of a blast-valve 9, which is located inside of the compressed-air tank 5, and which is normally pressed up against the open bottom end of the blast-tube 8, by any suitable means, preferably in the form of a valve-operating means which is accessible and operable from the bottom of said compressed-air tank 5.

The blast-valve 9 is in the form of an inverted cup, which is provided with a pressure-chamber l0 back of it, that is, underneath it, so that the blast-valve 9 is closed whenever compressed air is supplied. to its pressure-chamber l0, through a downwardly extending pipe I0. When the compressed air in thispressure-chamber I0 is dumped or evacuated, the air-pressure within the compressed-air tank 5 forces the blast-valve 9 open, so as to supply a strong blast of air to the interrupter-assembly I. The blast-valve 9 is illustrated as being provided with a light closingspring I l.

The bottom end 3' of the lower stationary contact-member 38 is supported in spaced relation within the funnel-like blast-tube 8, so as to provide an annular space 8s around said lower end 3 within said blast-tube. This supportingmeans for the lower end 3 of the bottom stationary contact-member 38 is shown in the form of a plurality of horizontal hollow or tubular bosses I? which serve jointly as the supportingmeans for the lOWer stationary contact-member 3S, and as the means for establishing a communication between the lower end of this contactmember 38 and the lower exhaust-chamber 3E.

The upper stationary contact-member HS is integrally or electrically united with an upper exhaust-chamber 413, which is similar to the lower exhaust-chamber 3E, except that it lacks the blast-tube 8. The upper stationary contactmember 4S is also of hollow construction. The lower end of this upper stationary contact-member 43 is provided with an orifice 4-0, which is normally closed by the upper movable contactmember 4M. The upper end of the hollow upper contact-member ts is in communication with the substantially closed space within the upper exhaust-chamber 4E. This upper exhaust-chamber 4131 is supported on the top of the upper insulating tube 4-1, the bottom end of which rests on the top of the outer cylinder To of the moving-contact housing 1. This upper insulating tube 4-I is also larger than the upper stationary contact-member 48, so as to provide an annular space 45, which forms a closed upper end for the blast-air, as this blast initially moves upwardly through th interrupter-assembly I.

As a result of the construction thus far described, when the blast-valve 9 is opened, a blast of air moves rapidly upwardly through the short blast-tube 3, the lower insulating tube 3-1, the outer cylinder 10, and the upper insulating tube 4-1, quickly creating an air-pressure which. forces open the two movable contact- members 3M and 4M against the pressure of their closing- springs 3B and 4B. In a sense, the entire tubular structure, including the elements 8, 3-1, lo and 4-1, may be regarded as comprising the blast-tube of the device. As long as a substantial air-pressure is maintained in this blast-tube, in the spaces surrounding the lower and upper gaps 3 and 4,

these gaps will be opened by the action of the air in pressing back the movable contact- members 3M and 4M, drawing an are at each gap. The compressed air of the blast will rush into the uncovered orifices 3-0 and 4-0 at the front or entrance-ends of the respective hollow stationary contact-members 3S and 4S, and will exhaust into the respective exhaust- chambers 3E and 4E.

As set forth in the application Serial No. 74,406, the size or volumetric capacity of each of the exhaust-chambers 3E and 5E is such that the pressure in, each chamber will build up to about half of the pressure of the blast-air surroundin the respective gaps, in about the time necessary to insure arc-extinction between the contact-gaps 3 and 4. This air-pressure, which is built up in the two exhaust- chambers 3E and 4E, is quite useful in pressurizing the gap-devices 3 and 4 at the moment of, and immediately after, the interruption of the arc, so as to increase the breakdown-voltage of the gaps, thus making is possible to use a shorter gap-separation, with a consequently faster operation because of the shortened gap-interrupting distance, and with smaller and less expensive parts.

As with all air-blast interrupters of this type. it is obvious that the movable contact- members 3M and 4M will remain open, only as long as an adequate air-pressure is provided in the regions immediately surrounding the gaps, as otherwise the closing- springs 3B and 4B will close these gapdevices. It is also obvious that it would not generally be feasible to maintain the fast-moving air-blast any longer than is absolutely necessary to safely interrupt the line-current and to guard against the restriking of the arc.

In common with other air-blast gap-devices of this general nature, therefore, I provide an isolating-switch Ht'which is electricall connected in series-circuit relation to the main interrupter-gap assembly I. In the illustrated form of embodi ment of my invention, one end of the isolatingswitch 16 is pivoted at I! to the bottom portion I" of the interrupter-assembly I. The free end of the isolating-switch I6 is movable into and out of contact with suitable contact-fingers [8 which are carried by a metal cap-piece I9 on top of an insulating supporting-column 2G. The metal cappiece 19 constitutes a line-terminal of my breakerassembly, being connected to the second lineconnection L2.

As shown and described in the application Serial No. 73,516, my isolating-switch I6 is operated by a pneumatic operating-mechanism or drive-mechanism 23, which is disposed at substantially ground-potential, being usually located on or near the ground. The operating mechanism 23 is provided with an operating-piston 24 which reciprocates a rack 25, which rotates a pinion 2% through a limited motion of approximately 180. The pinion-shaft 2'! has a drive-connection 28 to a crankshaft 29 having crank-members 3| which are connected to the isolating-switch l6 through an insulating switch-operating rod or linkage 32. The linkage-connection 32 is made in such manner that, at each of the extreme limits of the motion of the crankshaft 29, the insulated switchoperating rod 32 is in complete toggle, so that the isolating-switch I8 is locked in both its open position and its closed position, thus avoiding rebound.

The pinion-shaft 21 of the operating-mechanism 23 is illustrated as being provided with two auxiliary attachments. One of these attachments is a compression-spring linkage 40, which is crank-connected to the pinion-shaft 21, as indicated at in such manner that the compression-spring of this linkage 40 presses the pinion shaft 2'! toward either one of its limits of travel, once it has passed its central or 90 point in its travel from one extreme limit of motion to the other extreme limit of motion. This compression-spring linkage thus serves to hold the pinion shaft 21 in its extreme limit of motion, at either end of its direction of movement, so as to hold the crankshaft 29 in such position that the previously mentioned toggle-lock is provided, for holding the isolating-switch l6 against rebound.

The second auxiliary attachment which is associated with the pinion-shaft 2! of the operating-mechanism 23 is a shock-absorber, which is diagrammatically indicated at M, and which is crank-connected to the pinion-shaft 21, as indicated at 4|, in such manner as to strongly retard the last half of the rotating-movement of the pinion-shaft 21, during either direction of movement of said pinion-shaft. During the first half of the movement of the pinion-shaft 21, from either extreme limit of its motion, the

shock-absorber 4! is extended or lengthened, and

it offers practically no opposition to such lengthening movement. After the pinion-shaft 21 passes its midpoint or 90 point, it begins to contract the shock-absorber 4!, or to push together its telescoping cylinders. This contraction is very slow and gradual at first, but it becomes extremly rapid as the pinion-shaft 21 approaches the extreme limit or end of its motion. The shock absorber 4i opposes this contraction, with a force which increases very rapidly as the velocity of compression is increased.

The general-effect of this shock-absorber 4| is to slow down the speed of rotation of the pinionshaft 2?, particularly as it approaches the end of its motion, and as a result of this slow-down action, the pinion-shaft has a more nearly uniform speed of rotation or movement, as dis tinguished from-being constantly accelerated under the influence of the operating-force which is applied to it from the operating-mechanism 23, aswill be subsequently described. In fact, the reaction of the shock-absorber actually decreases the angular velocity of the pinion-shaft, at or near the end of its travel.

The operating-mechanism 23 includes also a double-piston air-valve 45, disposed with its two pistons 450 and 450 opposing each other. The left-hand air-valve piston 450, which controls the opening or" the isolating-switch I6, is preferably larger than the right-hand piston 450', which controls the closing of the isolating-switch [6. Each of the air- valve pistons 450 and 450 is provided with its own air-inlet pipe- means 460 and 460, respectively, for applying air, under pressure, to the respective air-valve pistons.

The air-valve is provided with ports 41, 48, 59 and 563,- which are so arranged that, when the switch-opening piston 450 is subjected to airpressure from its inlet-means 460, it moves to the right, thus closing the dump-port 4'! which dumps the air from the left-hand side of the operatingpiston 2 and at the same time it opens the inletport 48 which leads the inlet-air into this left hand side of the operating-piston 24 thus driving said operating-piston to the right, in a switchopening movement. At the same time, the abovedescribed movement of the left-hand air-valve piston o pushes the right-hand piston 450 over to the right, thus causing it to open its dumppoi't A9 and to close its inlet-port 5 0 which, when open, connects the space to the right of the operating-piston 24 with the closing-piston airinlet pipe-means 460.

It will be understood that the first-mentioned inlet and dumping ports 48 and 41 are both connected to the space to the left of the operatingpiston 24, while the other inlet and dumping ports 50 and 49 are both connected to the space to the right of the operating-piston 24, the two dumping-ports 4! and 59 being for the purpose of exhausting air to the atmosphere, while the respective inlet-ports 48 and 50 are for the purpose of supplying air-pressure to the operating-piston 24 from one or the other of the air- inlet pipes 460 and 460, as the case may be. By this means, I provide what is known as functional dumping, for dumping the air which would otherwise be trapped behind the operating-piston 24 when said piston is being moved in either direction of its travel.

In accordance with my present invention, I use the switch-opening air-valve piston 450 as a pressure-responsive control-mechanism, disposed at substantiallyground-potential, for controlling the initiation of the actuation of the drive-mechanism 23 in the switch-opening direction. To this end, I connect the switch-opening air-inlet pipe 460 to a vertical insulating pipe or aircommunicating means i, which extends up to the interrupter-assembly I, and which is in communication, through a pipe 52, with the inside of the blast-tube 8. The length of the insulating pipe 5| is at least approximately as long as the insulating-distance or height of the insulating supporting-means 2 for the interrupterassem- 1013 l, and this pipe-length is suflicient to provide a substantial time-delay between the blast-off of the air-blast interrupter-assembly and the application of an air-pressure from the blast-tube B to the control-mechanism 450 which causes an opening-movement of the isolating-switch H5.

In accordance with my invention, I provide a ,ine-fault-responsive means, of any suitable kind, for responding to fault-conditions which necessitate an opening of my breaker-assembly. Such a fault-responsive means is typified by an overcurrent relay 53, the operating-coil of which is energized from the line L2. The overcurrent relay 53 has a relay-contact 54 which is used to energize a trip-circuit 55 which energizes an electro pneumatic tripping-valve 56 which is used to control a reciprocating air-pressure motor 51. The motor 51 has a piston 58, and a pistonchamber 59 above said piston 58. An upwardly extending insulating piston-rod 60 serves to control the operation of the blast-valve 9, as will be subsequently described.

The electro-pneumatic tripping-valve 56 is connected, to the piston-chamber 59 through a pipe 62. In the normal deenergized position of this tripping-valve 56, as shown, the pistonchamber pipe 62 is exhausted to atmosphere. through the vent-port 63 of the valve. When the tripping-valve 56 is electrically energized, the pneumatic connection to the vent-port 63 is closed, and the piston-chamber pipe 62 is connected, instead, to an air-pressure pipe 64 which is connected to the compressed-air supply 6.

The top of the insulating piston-rod 60 of the air-pressure motor 51 is connected, through a walking-beam or lever 65, to a pilot dump-valve 66. In its normal non-actuated position, the pilot dump-valve 56 connects the pressure-chamber H] of the b1ast-valve 9 to the air-pressure; within the compressed-air tank 5, so as to keep the blast-valve 9 closed. When the piston-rod 60 is lowered, in response to the electrical energization of the electro-pneumatic tripping-valve 56, the walking-beam 65 moves the pilot dump-valve 66 upwardly, against the action of its biasingspring 61. When the pilot dump-valve 66 moves up, into its operated position, it closes off the connection between the pressure-chamber l0 and the compressed-air tank 5, and opens a vent-port 6B, which dumps the air from the pressure-chamber l0 and thus permits the pressure of the air in the compressed-air tank 5 to push open the blastvalve 9.

With a fault-responsive controlling-means as thus-far described, it will be evident that the blast-valve 9 will be opened Whenever there is a fault of predetermined magnitude on the line LlL-2; and it will be further evident that the blast-valve 9 will remain open as long as, and only as long as, the fault-responsive overcurrentrelay 53 continues to be actuated. As soon as the fault-current is interrupted, as by the interruption of the arcs drawn by the main gap-members 3 and 4 of the interrupter-assembly, the overcurrent relay 53 and hence the electro-pneumatic tripping-valve 56 will be instantly deenergized. Hence, pressure will be removed from the piston-chamber 59 of the air-pressure motor 51, and the piston-rod 60 will move up again, in response to the pressure of the biasing-spring 81 of the pilot dump-valve 66. In the same moment, the pilot dump-valve 66 will return to its normal non-actuated position, in which it supplies pressure directly from the compressed-air tank 5 to the pressure-chamber I0 of the blast- Valve 9, instantly closing the latter.

It is a desirable feature of my invention, that means shall be provided for obtaining a repeater-operation of my air-blast interrupterassembly 1, without waiting for the more sluggishly acting isolating-switch IE to open its con tact at the contact-fingers [8. It is also necessary, or exceedingly desirable, to build up pressure in the substantially closed exhaust- chambers 3E and 4E during the blasting-off of the interrupter-assembly, as previously described. If there is to be a repeater-action, some suitable means has to be provided for rapidly dumping the pressurized air in the exhaust- chambers 3E and 4E, whenever the blast valve 9 is reclcsed. Then, if a line-fault still persists, which has not cleared itself during the brief time during which the line has been deenergized by the action of the breaker, the overcurrent relay 53 will again instantly be actuated, as soon as the main gapdevices 3 and 4 close, thus instantly initiating a second blast-off operation.

In order to quickly dump the air from the exhaust- chambers 3E and 4E whenever the blast-valve 9 is reclosed, I provide each of these exhaust-chambers with a dump-valve 3D or 4D, as the case may be. Each of the dump-valves 3D and 4D is provided with a piston 15] which is provided with a piston-chamber Ti above it, and also a light-compression-spring 12 in this piston-chamber. When there is no externally applied air-pressure in the piston-chamber H, but air-pressure in the exhaust- chamber 3E or 4E as the case may be, the air-pressure of the exhaulst-chamber raises the piston 10 and. opens a vent-port 13, which quickly exhausts the air in the exhaust- chamber 3E or 4E as the case may be. When this exhaust-chamber air is reduced nearly to atmospheric pressure, the compression- 9 2. spring 12 pushes down the piston 10. and closes the vent-port l3. e

valves 3D and 4D are connectedto, an air-pipe 14, which is connected toa. pilot dump-valve 15.

The pilot dump-valve 15 is. operable-gin its non-i actuated position, as shown, to vent the pipe "I4 through vent-ports 16, so as to vent the pistonchambers H of the two dump-valves 3D and 4D. Under these conditions, there is no externally applied air-pressure on the dump-valves 3D or 4D, and these valves are free .to open in response to any substantial air-pressures which may exist Within their respective exhaust- chambers 3E or 4B. The pilot dump-valve 1'5 is held, in its illustrated non-actuated position, which is its uppermost position, by'meansofthe walking-beam lever 65 and the top end of the piston-rod 60 of the air-pressure motorfi'l.

When a fault occurs; the air-pressure motor 51 moves itg-p-istoh-rod 5i: downwardly, thus permitting the pilot dump-valve '55 to operate, under the bias of its compression-spring ll, thus closing the vent port 15-3 and connecting the dump-valve pipe 74 to-the pipe 52 whichis in communication with the inside of the blast-tube 8. As soon, therefore, as' the blast-off action begins, and pressure 'builds up in theblast-tube 8, external pressure is applied, through the pipe 52 and the (now-actuated) pilotdumpwalve 5, to the pipe I4 of the dump-valves 3D and 4D, thus holding these dump-valves firmly down in their closed-cit positionsso that, when air-pressure builds up inthe exhaust- chambers 3E and 4E, said exhaust-chamber pressure will not be able to open the dump-valves 3D and AD, as long as the pilotdump-valve 15 remains in its lowermostor operated position.

In any repeater-breaker assembly, some sort of counting-mechanism must be provided, for limiting the permissible number of times the breaker can keep on rapidly opening and closing automatically, in case of a permanent linefault which Will not clear itself.- To this end, I have shown, associated with the overcurrent relay 53, a self-resettable operation-counter 8?], which counts a predetermined number of rapidly recurrent breaker-operations, and then closes a make-contact 8| which energizes the trip-circuit 55 independently or" the continuance of a faultcondition. When this happens, the'blast-valve 9 isheld open, instead of reclosing as soon as the arcs have been interrupted at the'main gapdevices 3 and 4. The operation-counter 8B is i1- lustrated as having a second make-contact 32 which energizes a normally closed electrically operated switch-opening valve 83 in the switchopening inlet-pipe 460, so as to open this valve after a predetermined number ottreclosures; Pressure from the blast-tube 8 builds up at the bottom end of the insulating pipe 5i, andwhen the electrically operated switch-opening valve83 opens, it transmits the air-blastpressure from the blast-tube B to the switch-opening valve 450 of the operating-mechanism 23, thus initiating the operation of this operating-mechanism, and opening the isolating-switch l6. 1

In accordance with. the mode of operation which is provided for in the previously-mene tioned application Serial No. 73,516, the end of the operating-mechanism. rack 25 is provided with a switch-contact 84, which opens near the end of the opening-movement ofthe isolatingswitch It, and thus breaks the trip-circuit 55, thus deenergizing the electro-pneumatic trip- 10 ping-valve 55, causing the blast-valve 9 to be closed, and causing the dump-valves 3D and 4D to be opened.

Once the, operating-mechanism 23 has been actuated in a switch-opening direction, the isolating-switch I6 is locked open by toggle-action, so-that there is no danger of its rebounding closed again.

In order to provide means for reclosing the isolating-switch It, in orderto restore service to the line Li-LZ, I have provided an electrically energized switch-closing valve 85, which is illustrated as having an operating-coil which, when electrically energized, opens the closingvalve, and-admits compressed air from the pipe 64 to the switch-closing air-inlet pipe 460 of the air-valve d5 of the operating-mechanism 23.

The operation of my device has been explained as the description has proceeded, so that no further explanation should now be necessary.

, I wish it to be understood that I am not at all limited to the precise details which have been shown. The drawing has been very much idealized or simplified, in an effort to clarify the essential operation of the novel features which I have introduced in accordance with my ments, and as embracing all means. for performing the elemental functions or operations which I have combined for the first time in a useful circuit-interrupter assembly, as herein described. In other words, I desire to claim broadly all equivalent forms or Variants of the various means for performing or achieving the distinctive individual or elemental operations or steps leading tothe ultimate, composite result; so as to cover all machines having the distinctive essential law of action which I have described. There are also many details and safeguards, which will be apparent to those familiar with the art, many of which would be used in the actual practice of my invention.

While I have illustrated only one compressedair tank 5, which is used to supply an air-blast to two main gap-devices 3 and 4, I wish it to be understood that a separate compressed-air tank could be provided for each of the main gap-devices, each tank with its own blast-valve and blast-tube.

With the special dump-valves 3D and 41) which I have provided for the exhaust- chambers 3E and 4E, it is usually not necessary to provide will gradually exhaust the exhaust-chamber, in

readiness for another breaker-operation whenever another fault occurs. Usually this ventingoperation will be completed before the breaker potential and having 11 is restored to service, in the case of single-operation breakers.

I wish it to be understood, also, that my invention is not limited to the simultaneous use of all of the novel features which I have disclosed, as any one or more of the novel features may be employed, singly, or in various combinations with each other, within the intended scope of my invention. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language.

I claim as my invention:

1. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a sufficient insulatingdistance from a substantiall ground-potential surface to withstand. a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, a compressed-air tank also supported by said insulating supporting means at an elevated potential, a short blast-tube for at times supplying said interrupter-gap device with an air-blast from said tank, and a normally closed blast-valve for controlling the communication between said blast-tube and the tank, an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the main interrupter-gap device; a drivemechanism disposed at substantially groundinsulating drive-means connected to said isolating-switch for opening and closing the same; a pressure-responsive controt-mechanism disposed at substantially groundpotential for controlling the initiation of the actuation of said drive-mechanism in the switchopening direction; and communicating-pipe means for connecting said control-mechanism in responsive relation to the air-pressure within said blast-tube, said communicating-pipe means including an insulating pipe-length at least approximately as long as the insulating-distance of the insulating supporting-means for interrupterassembly, said pipe-length being suiiicient to pro-- vide a substantial time-delay between the blastofi of the air-blast interrupter-assembly and the application of an air-pressure responsive thereto to said control-mechanism.

2. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a suflicient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, an adjacently mounted compressed-air tank, a short blast-tube for at times supplying said interrupter-gap device with an air-blast from said tank, and a normall closed blast-valve for controlling the communication between said blast-tube and the tank, said main interrupter-gap device including a hollow elongated stationary contact-member having an orifice in its front end, a substantially closed exhaust-chamber at the rear end of said stationary contact-member in air-communication with its hollow interior, and a moving-contact assembly comprising a spring-closed, longitudinally movable contact-member normally abutting against the front end of said stationary contactmember and in such position substantially covering said orifice; in combination with: a pressureresponsive dump-valve for at times quickly dumping the compressed air out of said exhaust-chamber, said dump-valve being openable in response to air-pressure within said exhaust-chamber, and being closable in response to an externally applied airpressure; a pilot dump-valve operable, in its nonactuated position, to vent said dump-valve so that it has no externally applied air-pressure, said pilot dump-valve being operable, in its actuated position, to furnish said dump-valve with externally applied air-pressure from the blast-tube of the interrupter-gap device; and means for actuating both the blastvalve and the pilot dump-valve.

3. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a sufficient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, an adjacently mounted com pressed-air tank, a short blast-tube for at times supplying said interrupter-gap device with an air-blast from said tank, and a normally closed blast-valve for controlling the communication between said blast-tube and the tank, an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blastvalve during fault-free conditions; a counting mechanism for counting rapidly recurrent linefault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue independently of fault-conditions; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter-assembly; a drive-mechanism for opening and closing the isolating switch; a pressure responsive switch-controlling means for automatically controlling the actuation of said drive-mechanism in the switch-opening direction; a normally closed switch-opening control-valve in said pressure-responsive switch-controlling means; means associated with said counting mechanism for causing the opening of said control-valve at the end of a predetermined count of rapidly recurrent line-fault responses; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blastvalve.

4. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a sufiicient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, an adjacently mounted compressed-air tank, a short blast-tube for at times supplying said interrupter-gap device with an air-blast from said tank, and a normally closed blast-valve for controlling the communication between said blast-tube and the tank, an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blast-valve during fault-free conditions; a counting mechanism for counting rapidly recurrent line-fault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue independently of fault conditions; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter-assembly; a drive mechanism foropening and closing the isolating switch; a pressure responsive s vitch-controlling means for automatically controlling the actuation of said drive-mechanism in the switch-opening direction in response to the air-pressure in the blast-tube of the interrupter assembly; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve.

5. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a sufficient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, an adjacently mounted compressed-air tank, a short blast-tube for at times supplying said interrupter-gap device with an air-blast from said tank, and a normally closed blast-valve for controlling the communication between said blast-tube and the tank, an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blast-valve during fault-free conditions; a counting mechanism for counting rapidly recurrent line-fault responses and for operating, at the end of a predetermined count, to cause the operation of the blastvalve to continue independently of fault-conditions; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter-assembly; a drive-mechanism for opening and closing the isolating switch; a pressure responsive switch-controlling means for automatically controlling the actuation of said drive-mechanism in the switch-opening direction 'in response to the air-pressure in the blast-tube of the interrupterassembly; a normally closed switch-opening control valve in said pressure responsive switchcontrolling means; means associated with said counting mechanism for causing the opening of said control-valve at the end of a predetermined count of rapidly recurrent line-fault responses; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve.

6. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a suflicient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, a compressed-air tank also supported by said insulating supporting means at an elevated potential, a short blast-tube for at times supplying said interruptergap device with an air-blast ,from said tank, and a normally closed blast-valve for controlling the communication between said blast-tube and the tank, at

least one of the contacts of said main inter rupter-gap device being hollow and having an orifice at its front end and having a substantially closed exhaust-chamber at its rear end, the abutment of said contacts in the normal closed position of the interrupter-gap, device substantially covering said orifice; in combination with: a dump-valve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; means for actuating the blastvalve; and means for automatically actuating the dump-valveafter the substantial completion of the interrupting operation of the interrupterassembly. 1

'7. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supportingsaid interrupter-assembly at a sufficient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, a compressed-air tank also supported by said insulating supporting means at an elevated potential, a short blast-tube for at times supplying said interrupter gap device with an air-blast from said tank, and a normally closed blast-valve for controlling the communication between said blast-tube and the tank, at least one of the contacts of said main interrupter-gap device being hollow and having an orifice at its front end and having a substantially closed exhaust-chamber at its rear end, the abutment of said contacts in the normal closed position of the interrupter-gap device substantially covering said orifice; in combination with: a dump-valve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker; means for automatically actuating the dump-valve after the substantial completion of each interrupting operation of the interrupter-assembly; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter assembly; a drive mechanism for opening and closing the isolating-switch; and a pressure-responsive switch-controlling means for automatically controlling the actuation of said drive-mechanism in the switchwpening direction in response to the air-pressure in the blasttube of the interrupter-assembly.

8. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a sufficient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally of the interrupter-gap devices substantially covering said orifice; in combination with: a dump-valve which is operable at times to quickly dump the compressed air out of said exhaustchamber; an electrically controlled fault-responsive means for causing the operation of the blast-valve during linefault conditions on the circuit-breaker and for interrupting the operation of the blast-valve during fault-free conditions; a counting mechanism for counting rapidly recurrent line-fault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue independently of fault-conditions; means for automatically actuating the dump-valve after the substantial completion of each interrupting operation of the interrupter-assembly; an isolat ing-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter-assembly; a drive-mechanism for opening and closing the isolating-switch; a pressure-responsive switch-controlling means for antomatically controlling the actuation of said drive-mechanism in the switch-opening direction; a normally closed switch-opening contro valve in said pressure-responsive switchcontrolling means; means associated with said counting mechanism for causing the opening of said control-valve at the end of a predetermined count of rapidly recurrent line-fault responses; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve.

9. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a sufhcient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, an adjacently mounted compressed-air tank, a short blast-tube for at times supplying said interrupter-gap device with an air-blast from said tank, and a normally closed blast-valve for controlling the communication between said blast-tube and the tank, at least one of the contacts of said main interrupter-gap device being hollow and having an orifice at its front end and having a substantially closed exhaust-chamber at its rear end, the abutment of said contacts in the normal closed position of the interrupter-gap device substantially covering said orifice; in combination with: a dumpvalve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker trolling the actuation of said drive-mechanism in the switch-opening direction in response to the air-pressure in the blast-tube of the interrupter assembly; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve.

10. A compressed-air circuit-breaker assembly comprising: an air-blast interrupter-assembly; insulating supporting-means for supporting said interrupter-assembly at a sufficient insulatingdistance from a substantially ground-potential surface to withstand a substantial elevated linepotential; said interrupter-assembly comprising a main interrupter-gap device having normally closed contacts which are separable in response to an air-blast, an adjacently mounted compressed-air tank, a short blast-tube for at times supplying said interrupter-gap device with an air-blast from said tank, and a normally closed blast-valve for controlling the communication between said blast-tube and the tank, at least one of the contacts of said main interrupter-gap device being hollow and having an orifice at its front end and having a substantially closed exhaust-chamber at its rear end, the abutment of said contacts in the normal closed position of the interrupter gap device substantially covering said orifice; in combination with: a dump-valve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blast-valve during fault-free conditions; a counting mechanism for counting rapidly recurrent line-fault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue independently of faultconditions; means for automatically actuating the dump-valve after the substantial completion of each interrupting operation of the interrupterassembly; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter-assembly; a drive-mechanism for opening and closing the isolating switch; a pressure-responsive switchcontrolling means for automatically controlling the actuation of said drive-mechanism in the switch-opening direction in response to the airpressure in the blast-tube of the interrupter-assembly; a normally closed switch-opening control valve in said pressure responsive switchcontrolling means; means associated with said counting mechanism for causing the opening of said control-valve at the end of a predetermined count of rapidly recurrent line-fault responses; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve.

11. A compressed-air circuit-breaker assembly comprising: a compressed-air source; an airblast interrupter-assembly, said interrupter-assembly comprising a hollow elongated stationary contact-member having an orifice in its front end, a substantially closed exhaust-chamber at the rear end of said stationary contact-member in air-communication with its hollow interior, and a moving-contact assembly comprising a spring-closed, longitudinally movable contactmember normally abutting against the front end of said stationary contact-member and in such position substantially covering said orifice; a blast-tube for at times supplying said interrupterassembly with an air-blast from said compressedair source; a normally closed blast-valve for controlling the communication between said blast-tube and. said. compressed-air source; a pressure-responsive dump-valve for at times quickly dumping the compressed air out ofv said exhaust chamber, said dump-valve being openable in responseto air-pressure within said eX- haust-charnber. and being closable in response to an externally applied air -pressure; a pilot dump-valve operable, in its non-actuated position, to vent said dump-valve so that it has no externally applied air-pressure, said pilot dumpvalve being operable, in its actuated position, to furnish said dump-valve with externally applied air-pressure from the blast-tube of the inter rupter-assembly; and means for actuating both the blast-valve and the pilot dump-valve.

' 12. A reclosing compressed-air circuit-breaker assembly comprising: a compressed-air source; an air-blast interrupter-assembly, said interrupter-asseinbly comprising normally closed contacts which are separable in response to an air-blast; a blast-tube for at times supplying said interrupterassembly with an air blast from said compressedair source; a normally closed blast'valve for controlling the communication between said blasttube and said compressed-air source; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blast-valve during fault-free conditions; a counting mechanism for counting rapidly recurrent line-fault responses and for operating, at the end of a predetermined count, to cause the operation of the blast valve to continue independently of faultconditions; an isolating-switch; means for electrically connecting the isolating-switch in seriescircuit relation to the interrupterassembly; a drive-mechanism for opening and closing the isolating switch; a pressure-responsive switch-com trolling means for automatically controlling the actuation of said drive-mechanism in the switchopening direction; a normally closed switchopening control-valve in said pressure-responsive switch-controlling means; means associated with said counting mechanism for causing the opening of said control-valve at the end of a predetermined count of rapidly recurrent line-fault responses; and means responsive to an opening movements)? said drive-rnechanism for discon tlnuing the operation of the blast-valve.

13. A reclosing compressed-air circuit-breaker assembly comprising: a compressed-air source; an air-blast interrupter-assembly, said interrupter-assembly comprising normally closed contacts which are separable in response to an air-blast; a blast-tube for at times supplying said interruptei assembly with an air-blast from said compressed-air source; a normally closed blast-valve for controllingthe communication between said blast-tube and said compressed-air source; an

electrically controlled faultresponsive means for causing the operation of the blast-valve during line-fault conditions on the circuit'breaker and for interrupting the operation of the blast-valve during fault-free conditions; a counting mechanism for counting rapidly recurrent line-fault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue independently of faultconditions; an isolating-switch; means for electrically connecting the isolating-switch in seriescircuit relation to the interrupter-assembly; a drive-mechanism for opening and closing the 18 isolating-switch; a pressure-responsive switchcontrolling means for automatically controlling the actuation of said drive-mechanism in the switch-opening direction in response to the air pressure in the blast-tube of the interrupterassembly; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve 14. A reclosing compressed-air circuitbreaker assembly comprising: a compressed-air source; an airblast interrupter assembly, said interrupter-assembly comprising normally closed contacts which are separable in response to an airblast; a blast-tube for at times supplying said interrupter-assembly with an air-blast from said compressed-air source; a normally closed blastvalve for controlling the communication between said blast-tube and said compressed-air source; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blastvalve duringfault-free conditions; a counting mechanism for counting rapidly recurrentlinefault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue independently of fault-conditions; an isolating-switch; means for electrically connecting the isolatin -switch in series-circuit relation to the interrupter-assen bly; a drive-mechanism for opening and closing the isolating-switch; a pressure-responsive switch-controlling means for automatically controlling the actuation of said drive-mechanism in the switch-opening direction in response to the air-pressure in the blast-tube of the interrupter-assembly; a normally closed switch-opening control-valve in said pressure-responsive switch-controlling means; means associated with said counting mechanism for causing the opening of said control-valve at the end of a predeter mined count of rapidly recurrent line-fault responses; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve.

15. A compressed-air circuit-breaker assembly comprising: a compressed-air source; an air-blast interrupter-assembly, said interrupter-assembly comprising a hollow elongated stationary contact-member having an orifice in its front end, a substantially closed exhaust-chamber at the rear end of said stationary contact-member in air-communication with its hollow interior, and a moving-contact assembly comprising a spring closed, longitudinally movable contact-member normally abutting against the front end of said stationary contactmember and in such position substantially covering said orifice; a blast-tube for at times supplying said interrupter-assembly with an air-blast from said compressed-air source; a normally closed blast-valve for controlling the communication between said blast-tube and saidcompressed-air source; a dump-valve which is operable at times to quickly dump the compressed air out of said exhaustchamber; means for actuating the blast-valve; and means for automatically actuating the dump-valve after the substantial completion of the interrupting op-- eration of the interrupter assembly.

16. A compressed-air circuit-breaker assembly comprising: a compressed-air source; an airblast interrupter-assembly, said interrupter-assembly comprising normally closed contacts which are separable in response to an air blast, at least one of said contacts being hollow andhaving an orifice atits front end and having a substantially closed exhaust-chamber at its rear end; the abutment of said contacts in the normal closed position of the interrupter-assembly substantially covering said orifice; a blast-tube for at times supplying said interrupter-assembly with an air-blast from said compressed-air source; a normally closed blast-valve for controlling the communication between said blast-tube and said compressed-air source; a dump-valve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; means for actuating the blast-valve; and means for automatically actuating the dump-valve after the substantial completion of the interrupting operation of the interrupter-assembly.

1'7. A reclosing compressed-air circuit-breaker assembly comprising; a compressed-air source; an air-blast interrupter-assembly, saidinterrupt er-assembly comprising normally closedicontacts which are separable in response to an air-blast, at least one of said contacts being hollow and having an orifice at its front end and having a substantially closed exhaust-chamber at its rear end, the abutment of said contacts in the normal closed position of the interrupter-assembly sub stantially covering said orifice; a blast-tube for at times supplying said interrupter-assemblywith an air-blast from said compressed-air source; a normally closed blast-valve for controlling the communication between said blast-tube and said compressed-air source; a dump-valve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker; means for automatically actuating the dump-valve after the substantial completion of each interrupting operation of the interrupter-assembly; an isolatingswitch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter-assembly; a drive-mechanism for opening and closing the isolating-switch; and a pressure-responsive switch-controlling means for automatically controlling the actuation of said drive-mechanism in the switch opening direction in response to the air-pressure in the blast-tube of the interrupter-assembly.

18. A reclosing compressed-air circuit-breaker assembly comprising: a compressed-air source; an air-blast interrupter-assembly, said interrupter-assembly comprising normally closed contacts which are separable in response to an air-blast, at least one of said contacts being hollow and having an orifice at its front end and having a substantially closed exhaust-chamber at its rear end, the abutment of said contacts in the normal closed position of the interrupter-assembly substantially covering said orifice; a blast-tube for at times supplying said interruptei assembly with. an air-blast from said compressed-air source; a normally closed blast-valve for controlling the communication between said blasttube and said compressed-air source; a dump-valve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blast-valve during fault-free conditions; a counting mechanism for counting rapidly recurrent line-fault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue: independently of. fault-conditions; means for automatically actuating the dumpvalve after substantial completion of each interrupting operation of the interrupter-assembly; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter-assembly; a drive-mechanism for opening and closing the isolatingswitch; a pressure-responsive switch-controlling means for automatically controllin the actuatlon of said drive-mechanism in the switch-opening direction; a normally closed switch-opening control-valve in said pressure-responsive switchcontrolling means; means associated with said counting mechanism. for causing the opening of said control-valve at. the end of a predetermined count of rapidly recurrent line-fault responses; and means responsive to an opening movement of said drive-mechanismfor. discontinuing the operation of the blast-valve.

19. A reclosing compressed-air circuit-breaker assembly comprising: a compressed-air source; an air-blast interrupter-assembly, said interrupter assembly comprising normally closed contacts which are separable in response to an airblast, at least one of said contacts being hollow and having an orifice at its front end and having a substantially closed exhaust-chamber at its rear end, the abutment of said contacts in the normal closed position of the interrupter-assembly substantially covering said orifice; a blasttube for at times supplying said interrupter-assembly with an air-blast from said compressedair source; a normally closed blast-valve for corn trolling the communication between said blasttube and said compressed-air source; a dumpvalve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blastvalve during fault-free conditions; a counting mechanism for counting rapidly recurrent linefault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue independently of fault-conditions; means for automatically actuating the dump-valve after substantial completion of each interrupting operation of the interrupter-assembly; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter assembly; a drive-mechanism for opening and closing the isolating-switch; a pressure-responsive switch controlling means for automatically controlling the actuation of said drive-mechanism in the switch-opening direction in response to the air-pressure in the blast-tube of the interrupter-assembly; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve.

20. A reclosing compressed-air circuit-breaker assembly comprising: a compressed-air source; and air-blast interrupter-assembly, said interrupter-assembly comprising normally closed contacts which are separable in response to an air blast, at least one of said contacts being hollow and having an orifice at its front end and having a substantially closed exhaust-chamber at its rear end, the abutment of said contacts in the normal closed position of the interrupterassem bly substantially covering said orifice; a blasttube for at times supplying said interrupter-assembly with an air-blast from said compressedair source; a normally closed blast-valve for controlling the communication between said blasttube and said compressed-air source; a dumpvalve which is operable at times to quickly dump the compressed air out of said exhaust-chamber; an electrically controlled fault-responsive means for causing the operation of the blast-valve during line-fault conditions on the circuit-breaker and for interrupting the operation of the blastvalve during fault-free conditions; a counting mechanism for counting rapidly recurrent line-= fault responses and for operating, at the end of a predetermined count, to cause the operation of the blast-valve to continue independently of fault-conditions; means for automatically actuating the dump-valve after substantial completion of each interruptin operation of the interrupter-assembly; an isolating-switch; means for electrically connecting the isolating-switch in series-circuit relation to the interrupter-assembly; a drive-mechanism for opening and closing the isolating-switch; a pressure-responsive switch-controlling means for automatically controlling the actuation of said drive-mechanism in the switch-opening direction in response to 2 22 the air-pressure in the blast-tube of the interrupter-assembly; a normally closed switch-opening control-valve in said pressure-responsive switch-controlling means; means associated with said counting mechanism for causing the opening of said control-valve at the end of a predetermined count of rapidly recurrent line-fault responses; and means responsive to an opening movement of said drive-mechanism for discontinuing the operation of the blast-valve.

BENJAMIN P. BAKER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,175,902 Korndorfer Oct. 10, 1939 2,287,039 Jansson June 23, 1942 2,364,981 Journeaux Dec. 12, 1944 2,392,647 Cox Jan. 8, 1946 FOREIGN PATENTS Number Country Date 511,757 Great Britain Aug. 23, 1939 522,514 Great Britain June 20, 1940

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