US2575719A

US2575719A - Circuit breaker

Info

Publication number: US2575719A
Authority: US
Inventors: Winthrop M Leeds
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1946-06-25
Filing date: 1946-06-25
Publication date: 1951-11-20
Anticipated expiration: 1968-11-20

Description

Nov. 20, 1951 Filed June 25, 1946 W. M. LEEDS CIRCUIT BREAKER 4 Sheets-Sheet l ATTORN EY Nvfzo, 1951 w, M, LEEDS 2,575,719

CIRCUIT BREAKER ATTOR N EY W. M. LEEDS CIRCUIT BREAKER Nov. 20, 1951 Filed June 25, 194e ,/95 lNvENToR WU? ffl/"0p /7. L @e d5.

www JM ATTORNEY Nov. 2o, 1951 w. M. LEEDS 2,575,719

CIRCUIT BREAKER Filed June 25, 1946 4 snep-sheet- 4 Pressure )Dress z/re Time Tl'ne P21 e155 are Pressa/re '/m wf I; )A

110 706 115 113110 la@ H5 WlTNESSES: INVENTOR ATTORN EY Patented Nov. 20, 1951 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Application June 25, 1946, Serial No. 679,086

17 Claims. 1

This invention relates to circuit interrupting equipments, and more particularly, to a circuit breaker operated by fluid under pressure.

In recent years circuit breakers have been designed for operation by fluid pressure or compressed air mechanisms, and have been successfully employed in modern power systems wherein speed of response of each circuit breaker to development of a fault condition in the circuit is of prime importance. Compressed air operated circuit breakers have been developed in a number of diflerent types for various service conditions, one well known type being the so-called oil circuit breaker having contact means adapted to be moved to closed-circuit position by a piston operated by compressed air, and to open-circuit position under the force of a suitable spring or springs, upon tripping of a latch mechanism. Such a circuit breaker is illustrated and described in the application of James M. Cumming and R. C. Cunningham, Serial No. 410,686, filed September 13, 1941, now Patent No. 2,408,199, is- Sued September 24, 1946, and assigned to the assignee of this invention.

In a circuit breaker of the type referred to above, it is necessary to provide an operating mechanism that is trip-free either mechanically or pneumatically, so that when closing the breaker against a fault, the contacts will be made ready immediately to open at substantially the same speed as during a normal trip-out operation. A mechanical trip-free linkage system can be used to couple the fluid-pressure actuated piston to the contact structure by means of which the contact structure can be released from the operating piston and quickly moved to the open circuit position. This mechanical linkage system, however, has the disadvantage that it is quite complicated and costly to manufacture.

It is also desirable in breakers of the foregoing type, to provide means for effecting high speed reclosing of the breaker after it has been tripped in response to a fault in the circuit and to obtain immediate reopening in the event the fault persists. Several such reclosures in rapidsuccession, may be provided ior,'beiore the mechanism is nally locked outin cases where the fault does not clear. In high speed reclosing, the operating mechanism on at least the first trip-out, must be void of trip-free action so that fluid pressure can be applied under the operating piston to stop the contacts before reaching full open circuit position. On the nal trip-out the operating mechanism must be trip-free to prevent further attempts of reclosing in the event that the fault still persists. Mechanical operating mechanisms 2 have been devised which embody double latch schemes to effect two successive trip-outs but these structures also have the disadvantage of complexity and would not function if it is desired to make two or more quick reclosures in succession.

It has been found therefore, that for certain classes of service as above indicated, a pneumatically trip-free operating mechanism is preferable in that it is more flexible and simpler in principle of operation as well as being simple in construction. In its broadest aspect such a mechanism may provide means for quickly dumping uid under pressure from the operating cylinder to enable the operating piston to move with the contact means freed from any fluid pressure opposing such movement. To this end, it has been the usual practice to equip the circuit breaker with an auxiliary control circuit means operative to eiect energization of an electroresponsive dump valve simultaneously with energization of the usual electro-responsive tripping mechanism of the circuit breaker.

Experience has shown that this type of exhaust valve or dump valve is adequate for so-called pneumatic trip-free operation of a breaker employed in 'a GO-cycle service in which a satisfactory speed of parting 0f the contacts of the breaker may be as much as three to ve cycles. Applicant proposes to design still faster uid pressure operative circuit breakers, however, for service requiring a contact parting time of only one to two cycles, and has devised means for rendering the compressed air operative mechanism of such a breaker capable of even more rapid movement during a close-open cycle.

One object of my invention is to provide an improved fluid pressure operated circuit breaker having means for rapidly eliminating any force tending to oppose contact opening movement thereof in response to tripping of the breaker.

Another object of the invention is to provide a circuit breaker of the above type having means for quickly balancing the uid pressures acting on opposite sides oi the usual operating piston at a predetermined time of a close-open cycle of operation.

It is another object of the invention to provide a number of alternative forms of compressed air operative mechanisms for a circuit breaker, in which a dumping feature is combined with a new means for establishing an accelerating uid pressure which facilitates the desired rapid circuit opening movement of the circuit breaker operating parts.

Other objects and advantages of the invenlamavis Vtion will appear in the Afollowing more detailed description thereof, when taken in connection with the accompanying drawings, in which:

Figure 1 is an elevational sectional View, diagrammatic in form of a compressed air circuit breaker operating mechanism adapted to be equipped with auxiliary control means embodying the invention.

Fig. 2 is a fragmentary sectional View taken substantially along the line II-II of Figure 1, and embodying the invention in one form thereof;

Fig. 3 is a sectional view taken substantially along the line III- III ofthe combined dump and accelerating Valve device shown in Figure 2;

Figs. 4, and 6 are fragmentarysecti'onaluviews illustrating other forms of auxiliary control valve mechanisms constructed in accordance with the The latch mechanism 3| may be of any suitable design and, as illustrated, comprises a main latch member 32 journaled on a stationary pin 33 secured to the frame structure, a release pawl 34 pivotally connected to the frame structure by means of a pin for cooperation with the latch member 32, andan auxiliary latch member 36 adapted for cooperationV with the pawl 34. The main latch member 32 has a surface 38 adapted for latching engagement with the roller 30, and an extension 43 adapted for interlocking engagement with a portion of the pawl 34 for resisting counterclockwise movement of the main invention, all of which are adapted to'be used in connection with the 'apparatus shown in Figure 1.

Figs. 7, 8, 9 and 10 represent curves oi' pressure as a function of time for different exhaust valve arrangements that may be applied to the operating cylinder.

Figs. 11, l2 and 13 are diagrammatic positional views showing the progressive operation of the valvemechanism shown in Fig 3.

Referring to Figure 1 of the drawings, the circuit breaker operating mechanism therein illus.- trated constitutes a single pole unit of a iiuid pressure operated circuit breaker, having features of construction similar to those embodied in the circuit breaker described in the ,aforementioned patent Y application. The apparatus is .illustrated schematically as including-a suitable vframe structure (not shown) supporting stationary .contact .elements 5 in the power circuit to be controlled, a movable resilient contact .element 6 cooperative therewith and secured to a rod 1, a cylinder It! having mounted therein an operating piston or abutment Vl I, and a piston rod l2 operatively connected tothe rod 'l through the medium of an operating rod I3 and a beam i4. The beam Id is journaled on a stationary .fulcrumpin l5 and is pivotally connected at opposite ends to the respective rods 7 and I3. A coil spring I'I is mounted in cooperative relationship with the movable contact element 6 for urging that element toward an open circuit position. k

The piston II is responsive to the pressure of air f the piston Il .is subject to the pressure efz fluid in a low pressure -chamber 2|, which is adaptv.ed to be vented to atmosphere by way of a port I9 (see Fig. 2) as hereinafter explained. For maintaining'the circuit breaker elements 'just described in circuit closing position, the circuit .breaker apparatus is further provided with atransversely disposed beam 22, one end of which vis journaledfon a pin '.23 carried by Ya link 24 .that

is in turn pivotally connected to a pin 25 carried by the frame structure. The beam 22: is operatively connected .by means of a pin 28 tothe vpiston rod i2 at a point above the cylinder Il),

Aand also carries, at the end opposite the pin 23, aroller 33 which is adapted `to be Aengaged by a suitable latch mechanism, generally indicated at 3|, for holding vthe beam 22 and theassociated elements of the circuit breaker in theV circuit closing position, as showninFig. 1.

latch member about pin 33 under the force tending to raise the end of the beam 22 carrying the roller, andthus tending to effect disengagement of the latch member 32 from the roller. For biasing the main latch member 32 in a clockwise direction, there is provided a spring 42, which is mounted in an aperture formed in a suitable lug on the frame structure.

For tripping the latch mechanism 3l, there is provided an electroresponsive trip coil 44, which is adapted to be energized through the medium of a suitable trip control circuit (not shown) for causing upward movement of an armature carrying a plunger that is operatively aligned with one end of the pawl 34. The pawl 34 is normally urged .into the position shown in Fig. 1 by means of a spring 4l, which is adapted to yield upon operation of the pawl by the trip plunger 45. The auxiliary latch member 36 is inoperative when the parts are positioned as shown in Fig. 1, but servesto hold the pawl 34 .out of interfering engagement with latch member 32 when ythe beam 22 and other operating elements of the circuit breaker are in circuit opening position. A coilspring 49 is interposed between a recessed portion of the cylinder structure l0 and a lug 50 on the auxiliary latch 36, and acts to tilt the latter in a counterclockwise direction about pin 35, causing the lug 50 to carry the pawl 34 in the same direction, when the end of the beam 22 carrying roller 3l) is swung upwardly during an opening operation ofthe circuit breaker. It will be understood that a lug 5I carried on the upper end of auxiliary latch 36 is adapted to be engaged by the free end of the beam 22, when that beam is moved to the circuit closing position as shown in Fig. 1. With the auxiliary latch member 36 thus held down, the spring 41 is permitted to maintain the pawl 3d in interlocking engagement with the main latch member 32.

A reservoir is provided for storing a supply of fluid under pressure for operating the circuit breaker, the flow of fluid being controlled through the medium of a control Valve mechanism 6I. This control mechanism comprises a casing structure 63 secured in a suitable manner to the `cylinder l0, and having formed therein a valve chamber 64 communicating with the reservoir 60 andalso through a supply passage 65 with the piston chamber 20. Mounted in the valve chamber 64 is a valve element 61 having a stem 68 on Athe upper end of which is secured a collar V'Ill'. A coil spring 'il Vis interposed between the collar I0 and a shoulder formed on a valve seat member 72, for urging the valve element El -into engagement with an annular seat surface I3 formed on the seat member. Slidably mounted in a bore 'I'I formed in the casing 63 is a piston 18, which is normally held in an inoperative position asrshown in Fig. 1 by means of a coil spring'M, and which is engageable with stem 68 under pressure of uid in the bore 11 for unseating the valve element 61.

A pilot valve Amechanism is provided for controlling operation of the piston 18 and the valve element 61, comprising a valve element 80, which is operative to control communication from a passage 8| leading from the reservoir 60, to a passage 82 leading to the bore' TI. The valve element 80 is normally biased into seated position as shown in Fig. l and is connected through the medium of a stem 65 to a discharge valve element 86 formed on the lower end of an armature 81 mounted within an electroresponsive magnet coil 80. The magnet coil 89 is suitably mounted on a portion of the casing structure 63 and is adapted to be energized by means of the usual auxiliary control circuit for the circuit breaker. It is not deemed necessary to illustrate this control circuit inasmuch as the details of such'a circuit are well known in the art, one form thereof being disclosed, for example, in the aforementioned patent application of Cumming et al. It will be understood that upon energization of the magnet coil 89, the armature 81 is operated to eifect unseating of the valve element 80 and seating of the discharge valve element 86, thus establishing communication from the reservoir 50 to the bore l1 containing the piston 18.

Apparatus shown in Figures 2 and 3 n of section shown in Fig. 2 communicates with the high pressure chamber 20 by way of a passageway or port |05 and with the low pressure chamber 2| by way of a passageway |06.

The sectional View of the control device valve illustrated in Fig. 3 is taken substantially along the line 3-3 of Fig. 2, which is in turn a sectional view taken along the line 2-2 of Fig. l. Referring to Fig. 3, the bore |02 has slidably mounted therein a piston valve element ||0 for controlling communication between the passages and |06, and a separate vent valve element having a stem ||2 operatively aligned with the piston valve element ||0. 'Ihe vent valve element serves to control communication between an atmospheric exhaust port |I3 and a port H4 communicating with the passage |05. The piston valve element ||0 is provided with an extension terminating in a portion l5, which is also adapted to be brought into closing relation with the respective passages |05 and |06, and has a pressure face subject to pressure of iiuid admitted to a chamber I 'l formed in casing structure |0|. A coil spring ||9 is interposed between the piston valve element |0 and vent valve element for urging these elements apart, as shown in the drawing, while a second and preferably stronger coil spring |20 is interposed between the vent valve element and an end wall |2| of the casing structure. The vent valve element l l is thereby biased into the normal position illustrated, wherein communication f tact elements 5.

between ports H3 and ||4 isl cut off, while pistonvalve element ||0 is positioned to close com" ment with a stop shoulder |25 formed on the,

wall of the chamber For controlling the supply of uid under pressure to chamber l1, there is provided pilot valveelement |30, which is mounted in a valve chamber |3| communicating by way of a passage |32- with the passage |05. The pilot valve element |30 is normally biased into seated position as shown in Fig. 3 and is adapted to be unseated upon energization of a suitable electromagnet |33; for establishing communication from the valve chamber |3| through a passage |34 to the cham--A ber The iiow area of the passage |34 may be determined by proper adjustment of a plug member |36 having a screw-threaded engagement in a bore formed in casing |0|. If desired, the pilot valve mechanism may be provided with an additional vent valve portion (not shown) serving to insure venting of the chamber when the valve element |30 is seated in the same way as the valve 8B vents chamber 'l1 of the supply valve mechanism 6| shown in Fig. 1.

The compressed air operating means of the circuit breaker, including the piston and the associated elements already described, are operable to effect normal closing operations of the circuit breaker starting from a full open circuit position, and are also operable to effect a quick automaticreclosing operation of the breaker, wherein the reclosing movement is, initiated in an intermediate point in the opening stroke of the breaker after the main circuit to be controlled has been interrupted. The control circuits for controlling the energization of the electromagnet 89 associated with the supply valve mechanism 6|, and the trip magnet or coil 44 may be substantially the same as the control circuits disclosed in the aforementioned patent application, Serial No. 410,686. The electromagnet |33 is preferably connected in parallel with the trip magnet 44 in these control circuits, which have been omitted from the present disclosure in order to avoid undue complication of the drawings and description. It will be understood, however, that the trip coil 44 and the pilot valve electromagnet |33 are adapted to be energized in response to an overload or short circuit in the main circuit, which the circuit breaker is designed to protect.

In operation, while the circuit breaker equipment is disposed in its circuit closing position as shown in Figures l and 2, the beam 22 is held in a substantially horizontal position with the roller 30 in latched engagement with main latch member 32, so that the circuit breaker is held positively in the circuit closed position against any force tending to separate contact element 6 from con- In order to effect an opening operation of the circuit breaker, the magnet coil 44 is energized through the medium of the usual control circuit, as already explained, whereupon the plunger 45 is quickly raised to disengage the pawl 34 from the main latch member 32. Due to the relatively small area of contact between the inclined surface 38 of the main latch member and roller 30, the spring 42 is unable to resist the slight counterclockwise movement of the latch required to anemia-f release the beam 22, and the latter is consequent-f 1y moved upwardly about pin 23, while rod I3, beam I4 androd I are at the same time actuated bythe spring I1 to effect disengagement of the contact element 6 from the contact elements 5. The piston I is carried upwardly during the upward movement of the piston rod I2 with the beam v22. It is assumed that the pressure initiallyexisting in the piston chamber 20 is that of the atmosphere, by reason of Ya communication between the passage `|55 and atmospheric exhaust port 16, which is normally uncovered by the piston element 'I8 when in its uppermostposition, as'shown.

Ashereinbefore explained, the electromagnet I33,shown in Figures 2 and 3, is energized simul- -taneously with the energization of the trip magnet 44, in effecting the opening operation of the circuit breaker just described. Operation of the valve |30 by the electromagnet |33 at this time does not result in any functioning of the control valve device |00, however, since only atmospheric pressure exists in the piston chamber 20.

Assuming that the control circuit for the circuit breaker is now rendered effective by operation of the usual auxiliary reclosing means (not shown) to cause a closing operation, the resultant energization of the magnet coil 89 effects closure of exhaust valve element 86 and unseating of pilotvalve element 80, so that iiuid under pressure is admitted from the reservoir 60 to the bore I'I. The piston 'I8 is then forced downwardly to unseat the supply valve element 61 whereupon fluid'under pressure is supplied from the reservoir 60" through passage 65 to piston chamber 20. The circuit breaker piston II is thereby movedv downwardly and, through the medium of rods |2 and I3, beam I4 and rod 1, effects movement of the contact element 6 into bridging relation with contact elements 5, closing the main circuit.

vReferring to Figure 2, it-will be observed that the port I9, formed in the Wall of the cylinder I0, is so disposed as to permit fluid to be driven from the low pressure chamber 2| to the atmosphere during the initial downward movement of the piston II. Just before the piston I I reaches its lowermost position, however, it closes the port I9, so that a predetermined amount of fluid is bottled up in chamber 2| to cushion final movement of the piston. It will also be understood that fiuid under pressure admitted to the piston chamber 20 is free to flow through passage |05 and passage |32 to the valve chamber |3I containing the normally closed valve element |30.

`If the fault in the controlled or main circuit has not been removed at the time the automatic reclosure of the circuit breaker occurs, the trip coil 44 and electromagnet |33 are again energized, simultaneously with deenergization of the coil 89,

lthus yinitiating a reopening operation of the circuit breaker under the force exerted by the opening `spring I'I. According to my invention, the control valve device now becomes effective for facilitating the desired opening operation of the circuit breaker with maximum speed by causing vfirst a .rapid equalization of the iiuid pressures acting on opposite sides of the piston I and then dumping .any remaining fluid under pressure from the piston chamber 2|! to the atmosphere. This operation of the control valve device |00 will best be understood by reference to Fig. 3, it be- Y ing-:apparent that upon energization of the electromagnet |33 and consequent unseating of the valve element |30, fluid under pressure flows from they piston chamber 20 through the passages |05 and |32 and past the open valve to the pis-.-l ton chamber I I'I, and acts against the portion I I5,v

to force piston valve ||0 to the left overcoming the spring I I9.

During the first portion of its traverse, the piston valve IIO establishes communication be- .tween passage |05 and passage |06 (Fig. -11) to admit fluid under pressure from the piston chamber 20 to the low pressure chamber 2| on the opposite side of the piston II, thereby quickly equalizing the pressures acting on the piston. Upon continued movement of the piston valve element ||0 against the force of spring IIS, thev piston portion I I 5 thereof is brought into closing relation with the passage |06 (Fig. 12)., At the same time the piston valve element engages the end of the stem ||2 of the vent valvevelement' III, and carries that element slightly' out of its normal position against the force of spring |20. This slight movement of the valve element is sucient to admit uid pressure from the high pressure chamber 20 to the area between the valve elements H0 and I II. Since, at this time, the

chamber I Il has high pressure gas trapped therein, the valve element IIB-I I5 cannot move to- Ward the right and the valve element I|| is blasted to full open position (Fig. 13) by direct force of the high pressure gas exhausting from the high pressure chamber 20 through ports |I4 and ||3 to the atmosphere. The valve elements II and II-Ii are restored Ato their normal positions (Fig. 3) by the springs IIS and |20 when the pressure in the chamber 20 has been reduced to a predetermined value and the pressure hasleaked from the chamber I Il. The communication between passages |05 and |05 is thus vcut off just before the piston chamber 20 is vented to the atmosphere by way of passage I 05 and the ports II4 and I I3. It will thus be seen that for a brief interval of time, the entrapped fluid under pressure in the low pressure chamber 2| is rendered effective to accelerate the piston II upwardly to assist the usual circuit breaker opening spring Il (see Fig. l) in effecting the desired opening operation. When piston II uncovers the exhaust port I9, of course, the fluid under pressure remaining in chamber 2| is also vented to the atmosphere.

From the foregoing it will be evident that the auxiliary control valve device |00 is constructed and arranged to effect a reopening operation of the circuit breaker apparatus with a speed and freedom from resistance not heretofore attained by use of constructions heretofore proposed. The principal features of construction of the control valve device rendering possible this desired result include the equalizing valve element H0, which is operated only momentarily to permit fluid to flow around the circuit breaker piston II to balance the opposing pressure ,acting thereon, and the separate vent valve element III, which subsequently dumps air above the piston to atmosphere, allowing the iiuid under pressure trapped under the piston to accelerate the opening operation of the circuit breaker.

Apparatus sho-um in Fig. 4

In Fig. 4 of the drawings the invention is illustrated in a different form comprising an auxiliary control valve device |0011, which may be associated with the cylinder I0 of a circuit breaker apparatus having the same construction as that illustrated in Fig. l. The control valve device Ita comprises a casing |50 having a bore I'5I in which is Vslidably mounted' a valve piston |52, which is adapted to control communication from the piston chamber 20 to the atmosphere by way of a passage |a and an exhaust passage |53. The valve piston |52 is normally biased to its closed position, as shown in Fig. 4, by the force of a coil spring |56. A control electromagnet |33a and a pilot valve |30a operative thereby are provided for controlling the supply of fluid from the passage |05a to the upper face of the valve piston |52 in initiating the operation, as hereinafter explained. The circuit breaker operating piston ||a is in this case provided with normally closed valve means operative as the piston approaches its lowermost position to establish communication from the piston chamber 20 to the low pressure chamber 2| below the piston. This valve means may comprise a plurality of valve elements |60, each adapted to engage a suitable valve seat |6| and having a stem |62 extending downwardly through an opening |63 into operative alignment with the casing element closing the lower end of cylinder |0. A coil spring |64 is preferably associated with each of the valve elements |60 for biasing the element toward its seated position.

When fluid under pressure is supplied in the usual manner to the piston chamber 20 for eiecting a closing operation of the circuit breaker apparatus, shown in Fig. 4, the piston ||a is moved downwardly, it being understood that at this time the valve elements |60 are maintained in their closed positions, while piston valve element |52 is also seated to prevent escape of fluid from the piston chamber by way of the passage |050.. Just before the piston reaches the end of its downward stroke, however, the` stems |62 of the valve elements |60 are brought into engagement with the lower wall of the low pressure chamber 2|, so that the valve elements |66 are unseated to permit flow of the fluid from the piston chamber 20 to the chamber 2|. Thus, if the circuit breaker has been closed on a fault, consequent energization of the electromagnet |3341, together with the usual trip magnet, as hereinbefore explained, results in unseating of the pilot valve element |3011., and downward movement of the piston valve element |52 under the pressure of air thus supplied from the piston chamber 20, which is thereby vented to the atmosphere. The circuit breaker opening spring meanwhile begins to pull the piston rod .I2 and piston la upwardly, and the valve elements |60 are then closed by the respective springs |64 in time to trap some of the fluid under pressure in the low pressure chamber 2| to provide a momentary accelerating force assisting in the initial upward movement of the piston, until the piston uncovers exhaust port I9.

Apparatus shown in Fig. 5

In Fig. 5 there is illustrated still another form of auxiliary control valve device, indicated generally by the reference character |001), which -may be substituted for the control valve device |00 shown in Fig. 2, for providing certain of the operative features of that device. As shown in Fig. 5, the control valve device |00b comprises a casing structure |10 suitably secured to the cylinder l cuit for the circuit breaker.

In operation, assuming that the circuit breaker is closed upon a fault and that the usual tripping 4circuit is energized as hereinbeiore explained,

resultant energization of the electromagnet |331) effects opening of the pilot valve |12 during the initial upward movement of the piston by the usual circuit breaker opening spring. Upon unseating of the pilot valve element |12 fluid under pressure supplied to the passage |11 acts on the inner face of the valve piston |15 to force that element to its open position, thereby establishing communication between the piston chamber 20 and the low pressure chamber 2| at the opposite side of piston In this manner the uid pressures acting on the piston are substantially equalized in a shorter time than would be the case if the fluid under pressure in the piston chamber 20 were merely dumped to the atmosphere. It will be understood that the time required for equalization of the pressures above and below the piston can be minimized by suitably designing and proportioning the eleents of the apparatus shown in Fig. 5 so that the volume of the low pressure chamber 2|, while the piston Il is in a lower position as shown, will be only a fraction or about ten to twenty percent of the volume of piston chamber 20. Tests have indicated contact parting times as short as 11/2 cycles for a circuit ybreaker equipped with the equalizing control valve mechanism just described, as compared to usual contact parting times of approximately 2% cycles required in the case of a breaker having an ordinary dump valve arrangement.

Apparatus shown in Fig. 6

According to the invention as disclosed in Fig. 6, an auxiliary control valve device |000 is provided for accelerating operation of the piston in the course of an opening operation of the circuit breaker following closure thereof on a fault in the main line. Operation of the control valve device |000 is similar in principle to that of the control valve device |001) shown in Fig 5. Instead of merely equalizing the iluid pressures above and below piston however, the control valve device |00c is effective to accelerate the upward movement of the piston under the force of fluid under pressure supplied from a high pressure source such as the main supply reservoir associated with the circuit breaker.

As shown in Fig. 6, the control valve device |00c comprises a casing structure |90 adapted to be secured to the cylinder l0 of the circuit breaker by suitable means, such as bolts, and supporting an electromagnet |33c, which, like the electromagnet |33 shown in Fig. 2, is connected in the usual trip control circuit of the circuit breaker apparatus. Slidably mounted in a suitable bore in the casing structure is a valve piston |92, which is adapted to control venting of fluid under pressure from the piston chamber 20 by way of an exhaust passage |93. A coil spring |94 is interposed between a wall |95 formed within the casing structure and the valve piston |92 for urging the latter into its normal seated position, as shown in Fig. 6. The electromagnet |33c controls operation of a pilot valve element |98 which when unseated is effective to 1-1 supply fluid under pressure from the piston chamber 20 to a pressure surface of valve piston |92. Formed in the lowermost portion of the casing |90 is a valve chamber 200, which communicates by way of a pipe 20| with a suitable supply reservoir, such as the reservoir shown in Fig. 1. Contained in the valve chamber 200 is a supply valve element 202-having an operating stem 203, which is slidablymounted in scaling relation in a bore in wall |95 and carries an end element 205 operatively aligned with the valve piston |92. The supply valve'element 202 is arranged to control communication between the valve chamber 200 and a passage 201 leading to the low pressure chamber 2| of cylinder I0. For normally urging the supply valve element 202 into its seated position as shown in Fig. 6, a coil spring 209 is interposed between the wall |95 and the enlarged end element 205 of the stem 203.

In operation assuming that iiuid under pressure is trapped in piston chamber 20 at the moment When the circuit breaker is tripped, following a closing operation on a fault, energization of the electromagnet |33c in the usual manner reiects operation of pilot Valve |98 to supply fluid under pressure to the pressure face of piston valve element |92, which is thereby forced downwardly in opposition to the force of spring |94 for venting fluid from'chamber 20 to the atmosphere. Atthe same time the valve pistonelement |92 strikes the enlarged end elem-ent 205 of stem 203V and thus effects unseating of the supply valve element 202, so that iiuid at Amain reservoir pressure is quickly supplied to the low pressure chamber 2| below circuit breaker piston A positive upward force is thus exerted against the piston to increase the speed with which the circuit breaker is operated to its circuit opening position. It will be apparent, of course, that the supply valve element 202 will become operative only when the circuit breaker is tripp-ed while fluid under pressure is present in the piston chamber 20.

In order to show more clearly the advantages derived from the foregoing operating mecha-f1@ piston pushing down in a direction opposing 50 movem-ent of the piston to 'the open circuit position. The dashed 'lines of Figs. 8 to 10 'represent pressure under the piston pushing u'p to assist the accelerating spring in moving the contacts tothe open circuit position. The vertical arrows '255 represent the net force at a given time during operation. The time interval A'I' represents the critical time required to reverse the operating piston and obtain contact separation following initiation of the opening phase of the operation.

More specifically, Fig. 7 represents the pressure conditions above the operating piston of a pneumatically trip-free operating mechanism ofthe prior art in which the trip-free action is obtained solely by the use of a high-speed exhaust or dump valve which permits the compressed Huid above the piston to exhaust to atmosphere when closing the breaker on a fault so as to enable reversal of the piston with the breaker contacts to the open circuit position. It is apparent that the-retarding force on the piston decreases with the rate of decay of pressure above the piston.

In Fig. 8 pressure conditions are depicted in the arrangement of exhaust valve control as shown in Fig. 5 Ywherein the high pressure 'chamv:ber'Y 20 connected by way of passages yand `ments shown in Figs. 2 to 4 inA which a two step operation employed, the rst of which Aallows 'pressure yfrointhe high 4pressure chamber `20 to 'build 'up under the piston in chamber 25, thereby at least partially equalizing the pressure fon 'opposite sides or the pistonA and the second Vstep which seals oli the chamber 2| and at the same time opens chamber 320 to atmosphere so `a`s to provide an accelerating impulse on the under side offthe piston. -An inspection of lthe curves in Fig. Qfrevea'ls atonce vthat the performance of the apparatus shown in Figs. 2 to 4 is superior to that of apparatus shown in Fig. 5 or V`the prior art in that the time -AT actually includes an interval when uid pressure is accele- Vf'ratingftle piston upward to assist acceleratlingspring Hein opening the contacts.

The pressure conditions existing during 'closeopenope'ration of the 'arrangement shown `in Fig. 6 and :illustrated in the curves of Fig. 10 are generally similar to those shown in Fig. 9 with the exception that the pressure above the piston would decay more nearly as shown in Fig. 7. `Also 'the :pressure under the piston rises to a grate'rrvalue in that vit is supplied from the main 'reservoir 69 4or other suitable source. In thisjmstance th-e acceleration time interval during :the time AT is further increased over that jobtainedwith the'structures'of Figs. 2 to 4, thereb'yigiv'ing leven greater assistance tothe acceleraftingspring 'inopening the breaker contacts.

From vthe foregoing itV 'will now be 'apparent "that'the invention provides Vnovel structural and operational features for a nuid pressure actuatc'ircuijt breaker contributing to vthe speed of re'sponseof the "apparatus to a tripping impulse in'theeourseof a close-open cycle of operation.

'.'Ihie invention has been disclosed with reference toseveral'forms of'circuitbre'aker apparatus constructed 'and varranged in accordance therewith,

ibut vitis `:to be 'understood that various changes the v`str v .ictural 'details and ararngement of `'parts may 'be made without departing from 'the 'essential principles of the invention. It is des"ired'tlie're'fore that the language of the appended" claims be given the broadest (reasonable interpretation .consistent with vthe state of the prior art.

Having now described my invention, what I claim as new vand desire to secure by Letters Patent is:

1. -In a circuit breaker operative'by uid under pressurefand comprising relatively movable contactmeans, a cylinder, a piston in said cylinder for operating Asaid contact means and control valve means operative to control supply andrelease of fluid under lpressure to and from said cylinder in such a manner as to effect fast contact opening operation'of the circuit breaker on a close-open'duty cycle; the combination of auxiliary valve means controlling a communication for rapidly conducting fluid under pressure from one's'ide of said-piston to the other, and means for 'actuating said auxiliary valve means simultaneously with initiation of a fast-contact opening operation. i

i3 2. In a circuit breaker having r'ela-tively'movable contacts and fluid pressure operating mechanism arranged to effect fast contact opening operation of the circuit breaker on a close-open Aduty cycle including a movable abutment subject -to opposing pressures of fluid in a high pressure `chamber and in a normally vented low pressure chamber; the combination of valve means operative to supply and release fluid under pressure to and from said high pressure chamber in effecting normal contact closing and opening operations,

4other valve means biased to closed position and automatically operated to open position .during the closing stroke of a close-open operation to fvent fluid under pressure from said high pressure chamber and to supply fluid under pressure to said low pressure chamber for promoting high rspeed reverse movement of said abutment and rapid contact opening movement of the abutment during a close-open operation, and a venting port opened by said movable abutment during the opening stroke to vent said low pressure chamber to atmosphere.

3. In a circuit breaker having relatively movable contacts and fluid pressure operating mechw anism arranged to effect fast contact opening operation of the circuit breaker on a close-open duty cycle including a spring-biased movable abutment subject to opposing pressures of fluid in a high pressure chamber and in a normally -vented low pressure chamber, the combination of valve means operative to supply and release fluid under pressure to and from said high pressure -chamber in effecting normal contact closing and opening operations, means comprising a communication for conducting fluid pressure from vone side of said abutment to the other, auxiliary valve means operative to open said communication to balance the fluid pressures acting on said abutment for preventingretardation thereof on the contact opening stroke during a close-open operation, exhaust valve means operated by said auxiliary valve means to vent fluid pressure from said high pressure chamber, and an exhaust port uncovered by said movable abutment during an opening operation to vent fluid pressure from said low pressure chamber.

4. In a circuit breaker having relatively movable contacts and fluid pressure operating mechanism arranged to effect fast contact opening operation of the circuit breaker on a close-open Aduty cycle including a movable abutment biased tions, auxiliary valve means controlling .a communication bypassing said abutment and operative by fluid under'pressure in said high pressure chamber to effect substantial equalization of fluid .pressures on both sides of said abutment, .and

electroresponsive valve means operable on the opening stroke of a close-open cycle for admitting fluid pressure from said high pressure chamber to operate said auxiliary valve means.

5. In a uid pressure operated circuit breaker having movable contact means, biasing means for vbiasing said contact means toward open-circuit position, a cylinder and a movable abutment therein normally responsive to an increase in the pressure of fluid in said cylinder on one side of Athe abutment for moving said contact meansto closed-circuit position, the combination therewith of auxiliary Avalve means controlling a communication for supplying fluid under pressure to said cylinder for suddenly increasing the pressure of fluid on the opposite side of said movable abutment to facilitate a circuit opening operation of the circuit breaker by said biasing means, said auxiliary valve means comprising a normally low pressure valve chamber, a main valve element disposed in said valve chamber and subject to pressure of uid in said normally low pressure chamber, a springv normally holding said valve element seated, a pilot valve operable to admit iluid under pressure to said valve chamber for operating said valve element, and electroresponsive means for operating said pilot valve to open position.

6. In a iluid pressure operated circuit breaker having movable contact means biased toward open circuit position, a cylinder, a movable abutment operative in said cylinder for actuating said contact means, and control valve mechanism operative to open position to control supply and release of fluid under pressure to and from a chamber at one side of said abutment in effecting respective closing Iand opening operations of the circuit breaker, the combination therewith of auxiliary Valve means controlling a communication for diverting fluid under pressure from said chamber at one side of the movable abutment to the chamber at the opposite side thereof, and electroresponsive means operable simultaneously with the closure of said control valve mechanism upon initiation of a contact opening operation to effect actuation of said auxiliary valve means to open said communication.

7. In a fluid pressure operated circuit breaker -having movable contact means biased toward open circuit position, a cylinder, a movable abutment operative in said cylinder for actuating said contact means, and valve means for supplying fluid under pressure to a flrst chamber in said cylinder at one side of the abutment for effecting a circuit closing operation of said contact means and operative to release fluid under pressure therefrom in initiating a circuit opening operation, the combination therewith of auxiliary valve means comprising a first auxiliary valve controlling a communication for conducting fluid pressure from said rst chamber to a second chamber on the other side of said abutment and operative by fluid pressure upon initiation of a circuit opening operation to establish communication from said rst chamber to said second chamber at the opposite side of the abutment, a second auxiliary valve controlling a relatively large exhaust port and operable by said rst auxiliary valve to vent fluid from the ilrst mentioned chamber to the atmosphere and an electromagnetically operated pilot valve for admitting fluid pressure to operate said rst auxiliary Valve.

8. In a fluid pressure operated circuit breaker lhaving movable contactv means biased toward open circuit position, a cylinder, a movable abutment operative in said cylinder for actuating said contact means, and an electroresponsive' control valve means adapted to be rendered operable at one `time to supply fluid under pressure to a `chamber in said cylinder at one side of the abutment for initiating a contact closing operation of the circuit breaker and at another time to 'vent fluid from said chamber for'permitting a circuit opening operation thereof, the combination itherewith of an auxiliary valve mechanism, comprising a rst auxiliary valve means operative by fascisme uidipressure upon lnitiationof 'a contactfopening :operation 'to augment the discharge lof .fluid under pressure from .said chamber at onesside 'of the abutment, a second auxiliary 'valve means operable .by said lirst auxiliary valve .means for effectingmomentary `supply 'of fluid under pres- 1sure to the chamber :at the opposite Iside lof the abutment, .and iel'e'ctroresponsive' means operable 'upon initiationofV a contact openingoperation to 5admit luid pressure to operate .-said: rst auxil- .iary valve means.

29... In a circuit breaker .having relativelyl movable contacts :and .fluid pressure opera-ting mechanismt-arranged to 'effect fast contact openingfop.- eration. ofthe circuit .breaker on Va` close-open duty cycle including a .spring-biased movable abutment subject to opposing pressures of `fluidi-in a high pressure chamber and in a low pressure chamber, lthe l'combination of `valve meansopera- -tive tosupply and release iiuid under 'pressure to and from said .highV pressure-chamber neie'cting normal contact closing and opening :operations, and auxiliary valve means comprising :a first lauxiliary valve controlling .a communica-tion Ibetween .said high and low pressurev 'chambers Yandoperative :by fluid pressure upon initiationof a. contact opening stroke of 'said .abutmentrst to 'establish 'communicationbetween said high and .low pressure chambers and then to :close .said fcommunicatiomand:asecond auxiliary A'valve 'conltrollingV an exhaust port and operated :by said rstauxiliary valve when `'said rst valve closes said Acommunication 'to vent said high 'pressure rchamber to the atmosphere.

10. In a circuit breaker ahaving .relatively .movable contacts and fluid pressure operating rmechanism arranged to effect fast contact opening `operation of the circuit breaker on a close-open -duty cycle Aincluding a spring-biased `movable abutment subject to opposing 'pressures of .fluid 4in a high pressurechamber and in :a low pressure chamber, ytheicom-bination of control valvemeans operative to vsupply and release uid under pressure to and from said high pressure chamber in Veffecting normal contact closing and openingfopera-tions, means comprising a passage communicating said high and low pressure chambers, `and `auxiliary valve means operative Irst "tobalanc'e the `opposing fluid pressures racting 'on :said abutment and then to vent'fluid runder :pressure from :said high pressure chamber, .said :auxiliary 'valve means comprising Va cylinder, a rst valve .member disposed in ysaid cylinder comprising spaced :integral valve Aelements 'operable 'by `iiuid pressure to rstopen and then close said communication :to effect-a momentary .flow-of uid pressure from 'said high pressure chamber to .said/low. pressure chamber, mea-ns comprising Ia vent. port, a ven-t valve' disposed in said cylinder in spaced l:relation -w-ith said first valve member .and normally closing said vent port, said rst valve member when operated a predetermined distance 'engaging and operating said vent valve to 'open 'said lvent port, `andmeans operable to admitfluid to saidfcyl-inder to operatesaid auxiliary -va'lvemeans y1.1. -In a circuit breaker having relatively Sinnvable contacts and vfluid Vpressure operatingmechanism arranged to elect fast contactgopeningfoperation 'of the circuit lbreaker 'on .a close-open duty cycle fincludinga .cylinder and 'a .springlbiased movable abutment 'subject fto opposing pressures. of iluid in a high pressurechamberand in 4a low pressure chamber, the combination of valve means'operative tosupply and release A`fluid under pressure -to and .from .said J'hig-h pressure vcl-ramber in effecting .normal :contact closing and opening operations, auxiliary-valve means .opera-- tive to balance .the uid pressures acting onsaid abutment ffor preventing retardation thereof the opening .stroke during a close-open sopera.- tion, Asaid auxiliary valve means 'including .a nor-- mallyseated valve element mounted insaid vabutment :and lmechanically operable to open 'position `by engagement with said cylinder to establish communication between said high and low .pressure chambers only when said-.abutment reaches a predetermined position .near `the end 'of itscon- 'tact closing stroke, and an exhaust 'port uncovered by .said movable .abutment Vafter :a 'predetermined movement in opening direction Ato vent iluid `under pressure from said iloW lpressure chamber.

12. a circuit breaker Vhaving relatively mov.- Iable contacts andiluid Vpressure yoperating mecha- 'nism .arranged to effect fast contact opening .operation of the circuit breaker on a "'clcse-open vduty cycle including. a .spring-biased' movable abutment subject to opposing pressures .ci ilu'd -in :a high pressure chamber kand in .a Lnormally vented :low .pressure chamber, the combination of controlvalve means operative to supply .and release fluid under pressure to and from said Jhigh pressure chamber in eiecting normal contact yclosing and opening operations, :an exhaust valve operable by fluid pressure in -sai'd high-.pressure chamber to vent said highpressure chamber, 4electroresponsive means operable on theiinitiation :of the opening stroke of ;a"c`los`eopen .cperationlto admit vfluid pressuref-to saidexhaust valve .to e'ffeet. opening 4of said vexhaust valve, andan .au-xiliary valve disposed 'to be engaged and :movedito open position by said exhaust valve `vvhen said exhaust valve vmoves to open .position to admit fluid pressure to said `10W :pressure chamber.

13. 'In a circuitfbreaker having'relatively .movable .contacts andfiuid `pressureaoperating mecha- `nism arranged .to effect .rast contact opening .op-

eration lof the circuit breaker fon a fclose-open 'duty cycle including :a spring-biased. movable Y vabutment subject to opposing pressures of Afluid Jin a .high pressurechamber andina low pressure chamber, the combinationl of control valve means operative vto vsupply and .release -uid zunder pressure to and `from said .high pressure :chamber .in

effecting normal feontactelosing and opening-operations, van exhaust valve operative by fluid pressure upon -the .initiation vof the y'openin'gstroke of 'a close-open :operation to vent said. high pressure chamber, an auxiliary valve foperable 'by said exhaust valve for admitting a :momentary vsupply of fluid under :pressure to said low lpressurefchamber, electroresponsive .means operable upon .initiationof an opening operation to admit Huid pressure tooperate said exhaust valve, andan exhaust port opened bysaid abutment :during an 'opening `loperation Athereof to vent said momentary sup- ;ply :of luid under .pressure `from said low pres- :sure chamber.

i4. l'In 'a circuitxbreaker having relatively movable contacts and fluid pressure 'operating mecha- .nism arranged -to 4eiect .tast contact opening operation of vthe circuit breaker 'on a close-open duty4 cycle lincluding :a spring-:biased movable abutment 'subject to opposing pressures-of lhuid in a high pressure chamber `and Vin a normallylow pressure chamber, the combination of control valve .means operative to open .and c'losed posiitions to supply Sand vent Vfluid pressure to and ifrom said fhigh pressure chamber in eiectingnor- Vmarcontactclosingandopening operations, aux- 1? iliary valve means controlling a passage ior supplying iiuid under pressure to said normally low pressure chamber for suddenly increasing the pressure of iiuid in said low pressure chamber to facilitate a fast circuit opening operation oi the circuit breaker by said biasing means, electroresponsive means operative upon initiation of the opening operation of a close-open duty cycle for actuating said auxiliary valve to open position,

and a venting port opened by said movable abutg ment during the opening stroke to vent said low pressure chamber to atmosphere.

15. In a circuit breaker having relatively movable contacts biased toward open-circuit position and fluid pressure operating mechanism arranged to facilitate fast contact opening operation of the circuit breaker on a close-open duty cycle including a movable abutment subject to opposing pressures of fluid in a high pressure chamber and in a normally vented W pressure chamber, the combination of valve means operative to supply and release fluid under pressure to and from said high pressure chamber in eiecting normal contact closing and opening operations, an exhaust port for venting said high pressure chamber to atmosphere, Ia normally closed exhaust valve controlling said exhaust port, other valve means controlling a passage for supplying fluid under pressure to said 10W pressure chamber to suddenly increase the pressure oi iiuid in said loW pressure chamber to facilitate a fast circuit opening operation of said circuit breaker, electroresponsive means operative simultaneously with the initiation of the opening stroke of a close-open operation to effect movement of said exhaust valve to open position to lvent said high pressure chamber, and said exhaust valve engaging and Iactuating said other valve means to open position to supply fluid under pressure to said loW pressure chamber,

16. In a iiuid pressure operated circuit breaker having movable contact means, biasing means for biasing said contact means toward open-circuit position, a cylinder, and a movable abutment therein normally responsive to an increase in pressure of uid in said cylinder on one side of said abutment for moving said contact means to closed-circuit position, the combination therewith of auxiliary valve means operative by iiuid pressure on said one side of said abutment for controlling a passage for supplying fluid under pressure to said cylinder on the opposite side of said abutment only on the opening stroke of a closeopen operation for suddenly increasing the pressure of iiuid on the opposite side of said movable abutment to facilitate a fast circuit opening operation of said circuit breaker by said biasing means, electroresponsive means operative upon initiation of a fast opening operation of said circuit breaker to admit iiuid pressure to actuate said auxiliary valve means to open position, and a venting port normally closed by said movable abutment and opened by said abutment during an opening operation to vent said cylinder on the opposite side of said abutment to atmosphere.

17. In a circuit breaker having relatively movable contacts and fluid pressure operating mechanism arranged to effect a fast opening operation of the circuit breaker on a close-open duty cycle including a movable abutment subject to opposing pressure of fluid in a high pressure chamber and in a normally low pressure chamber, the combination of Valve means operative to admit a closing change of uid under pressure to said high pressure chamber to eiTect a normal contact closing operation, auxiliary valve means responsive to said closing charge of fluid under pressure in said high pressure chamber and operable to admit a momentary charge of iiuid under pressure to said low pressure chamber to effect highspeed reversal of movement of said abutment to thereby acilitate a fast opening operation of said contacts, and means operative simultaneously with the initiation of the opening stroke of a close-open operation to initiate opening of said auxiliary valve.

WINTHROP M. LEEDS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STA'IES PATENTS Number Name Date 112,385 Sellers Mar. 7, 1871 433,822 Robb Aug. 5, 1890 513,601 Teal Jan. 30, 1894 2,233,521 Ernst et al. Mar. 4, 1941 2,286,023 Strang June 9, 1942 2,292,096 Thumin et al. Aug. 4, 1942 2,360,687 Johnson Oct, 17, 1944 2,408,199 Cumming et al Sept. 24, 1946 2,420,872 Easley May 20, 1947