US2575934A - Automatic valve controlling mechanism for electric circuit breakers - Google Patents

Description

O 1951 J w. TIMMERMAN, JR 2,575,934

AUTOMATIC VALVE CONTROLLING MECHANISM FOR ELECTRIC CIRCUIT BREAKERS Filed Nov. 18, 1947 Fi l.

Inventor" Julius W. Timmerman Jn,

H is Attorney.

Patented Nov. 20, 1951 AUTOMATIC VALVE CONTROLLING MECHA- NISM FOR ELECTRIC CIRCUIT BREAKERS Julius W. Timmerman, Jr., Waukesha, Wis., assignor to General Electric Company, a corporation of New York Application November 18, 1947, Serial No. 786,594

8 Claims. 1

My invention relates to fluid control means for electric circuit breakers and, more particularly, to an automatically operable mechanism for controlling the degree of opening of a blast valve used to supply fluid to a'circult breaker of the fluid actuated type.

Circuit breakers utilizing a blast of fluid to extinguish the are drawn between retractable contactsmay also utilize the fluid blast to perform the retracting action of the contacts and, therefore, the amount of fluid required may be quite large. This is particularly true if the circuit breaker is of the reclosing type where several operations may be performed within a relatively short period of time, thus necessitating the use of a relatively large storage tank or reservoir for the fluid.

In circuit breakers employing biased-closed interrupting contacts, an isolating switch is placed in the main circuit in series with the circuit breaker interrupting contacts. In such cases, after a circuit interrupting operation is performed by the circuit breaker, the circuit breaker interrupting contacts must be maintained in the open position sufliciently long to permit the isolating switch to form a sufllcient isolating gap. The rate of flow and pressure of the fluid necessary to maintain the circuit breaker interrupting contacts in the open position after interruption has been accomplished may be considerably less than that required for the dual purpose of both holding these contacts open and blasting the are drawn therebetween to extinction.

A principal object of my invention, therefore, is the provision'of means whereby the overall consumption of fluid may be substantially reduced thereby making possible a smaller fluid storage capacity than ordinarily would be required for a particular circuit breaker application.

Another object of my invention is the provision of means for supplying a relatively large quantity of fluid for the purpose of causing the circuit breaker contacts to separate and at the same time to blast the arc to extinction followed by a substantial reduction in the quantity and pressure of fluid supplied for the purpose of maintaining the contacts separated and insulated from each other until such time as the isolating switch blade will have formed a suitable series isolating gap.

Still another object of my invention is the provision of means for initially causing the main blast valve to assume its fully opened position for a predetermined time and thereafter to revert to an intermediate or partially opened po- 2 siticn whereby the amount and pressure of fluid supplied to the circuit breaker may be reduced after the interruption of the circuit.

A further object of my invention is the provision of piston means automatically operableinresponse to pressure supplied from the fluid tank or reservoir for controlling the main blast valve and thereby to conserve the amount of fluid required to perform a circuit interrupting operation.

Other objects and advantages of my invention will become apparent from the following description taken in conjunction with the accompanying drawing, in which: Fig. 1 represents a circuit interrupting arrangement incorporating a blast valve operable by two piston members to opened,

conduit 14, branch conduits i6 and H to the circuit breaker schematically represented and generally indicated by the numeral l8. Fluid from auxiliary conduits l6 and I1 enters the circuit breaker housing 20 to occupy chambers 22 and 24. Thus fluid pressure in the chambers 22 and 24 bears against the surfaces of pistons 28 and 2! to which main contacts 32 and 30 are secured. The pressure of the fluid forces pistons 26 and 28 apart against the action of biasing springs 34 and 36 to draw an are between contacts and 32 in the enclosure 38. As the contacts 30 and 32 pass through the throats 40 and 42 respectively, a blast of pressure fluid is caused to new from the chambers 22 and 24 into the enclosure 38 where a blasting action takes place which is suiflcient to extinguish the arc and to expel the products of the interrupting operation such as gas and other materials to atmosphere through the exhaust vent 45.

The circuit interrupting operation may be initiated by manually closing the switch schematically indicated at H which operation supplies a current from a source of potential, not shown. to the coil 46 which in turn picks up the armature 48 against the bias of spring 5,0 to cause the plug member 52 of pilot valve 53 to rotate counterclockwise due to the upward movement of the arm 54 thereby causing the passage 56 in plug mango ically represented at 80 to energize the winding '00 of relay 02 causing armature in to move upwardly thereby completing the circuit to the re- .lay coil 40.

The valve mechanism oi Fig. 1 will now be described. RodJ2 is rigidly secured as by a pin I4 to blast valve disc I2. Piston It is slidable within cylinder I0 and is secured to rod I2 by any suitable means such as by pin I. Spring 82 may be used for the purpose of biasing piston It. rod I2 and'valve disk I2 to the closed position. A port such as 80 may be provided in cylinder I8 to insure communication between atmosphere -and the underside of piston I6. Port 86 will prevent the entrapment of fluid under piston It as for instance when the piston is moving downwardly. If it is desired to utilize the cushioning effect of fluid under piston It, the port it may be omitted. Piston 28 is slidably mounted on shaft I2 within cylinder 00. Spring 92 biases piston 00 away from the common end wall or partition 04' which separates the two cylinders I8 and 40. Suitable ports or vents 93 may be drilled through the piston 00 in the direction of its axis. The capping member St is secured to the rod 12 in any suitable manner such as by a set screw 08. Radially extending ports I02 and I04 are provided in the hollow portion II of the rod I2. Needle valve I06 is slidably adjustable within the hollow portion III of the rod I2 for the purpose of controlling the flow of fluid from the hollow portion ml of the shaft I2 through the vents I02 into the cylinder- 90. Thus, it will be seen that the ports I02 and I04, the hollow portion IOI of rod- 12 together with the central opening in partition 94 form an auxiliary valve interposed between cylinders I8 and 90. The adjusting mechanism for needle valve I 08 may comprise internal threads on the inner surface of hollow .portion III of rod I2 at .the upper end of rod I2 and exend of rod I2 and which would engage the external threads on needle valve I 06.

-As shown in Fig. l the valve I2 is inthe closed position. In this position there is no pressure in the portion 59 of conduit 58. Piston I6 is biased upwardly by thespring 82 and a small clearance exists between the upper surface of piston It and the lower surface of the common end wall 86. In the position shown in Fig. l the ports 83 are uncovered so that atmospheric pressure may exist inside the cylinder 90. When the valve I2 is in its intermediate and opened positionsthe capping member 06 abuts against the upper surface of piston 08 to seal the ports 93. The clearance distance between the upper surface of piston 88 and the lower surface of capping member 96 is also the distance of travel of valve I2 and its assoelated parts from the intermediate position to the closed position of valve l2 as will be more fully valve closed position shown in Fig. i, the piston 00 is biased upwardly by its spring '2 into abut ting relationship with the apertured outer. end wall 0I of cylinder 00.

For the purpose of supplying a relatively large blast of pressure fluid to the circuit breaker II to perform a retracting operation of the contacts 20 and 32 and also to blast the are drawn therebetween, it is necessary to cause the valve I2 to assume its fully opened position. To accomplish full opening of the valve I2, plug member 52 o'f the pilot valve 03 is rotated counterclockwise by energizing coil 4| either manually or through a current transformer as explained above. Pressure fluid from reservoir II passes through conduit ll, pilot valve 52, portion 59 of conduit 50 and .through an opening in the common end wall or partition '04 to the inside of cylinderflt. It will be observed that ports I04 in rod I2 are covered. Fluid pressure against the upper surface of piston It will force that piston, the rod l2, and the valve I2 to move downwardly against the bias oi spring l2 until the valve I2 has reached its fully fopened position. As the rod I2 moves downwardly, the capping member 86 engages the upper surface of piston "and forces that piston downwardly against the bias of spring 02. After the rod I2 has moved a slight distance toward the fully opened position of valve I2, the ports I04 in rod I2 are uncovered as they clear the common end wall 84. Pressure fluid then passes from cylinder ll through ports I04, the hollow portion III of rod I2 and the ports I02 in rod I2 and thence into the cylinder 90. The rate at which pressure builds up in cylinder 90 is controlled by the particular setting to which needle valve I06 has been adjusted. Preferably the setting of needle valve I08. the size and position of openings 502 and I04 will be chosen to permit valve I2 to reach its fully opened position and to remain in that position long enough to insure the extinguishment of the arm drawn between contacts 20 and 32 of circuit breaker I8. It will be observed that the maxi- .mum travel of piston I0 and rod I2 toward the opened position of valve I2 is limited by the shoulder I9 in the cylinder I0. Preferably the quantity of fluid allowed to pass into cylinder during the opening operation of valve I2 will be 'sufllcient to aii'ord a pneumatic cushioning action which will .serve yieldably to arrest downward motion of piston 80 and, in turn, the downward motion oi valve i2, rod I2 and piston It. As discussed above, the needle valve I06 will haveioeen so adiusted that valve I2 will be forced to remain open for a long enough time to permit estinguishment o! the arc between retractable contacts as and 32.

As explained above, in order toconserve the amount of fluid required to perform an interrupting operation, it is desirable. to reduce the fluid flow after the arc has been extinguished and pending the formation of a suillcient isolating gap by the series connected isolating switch. To accomplish this purpose in accordance with my invention. the valve is causedto move toward its closed position to occupy an intermediate or partially opened position which will reduce the quantity of fluid flow to an amount Just suiiicient to maintain the circuit breaker contacts in their isolating po 0 Assuming that the main valve I2 is fully opened. the operation of my invention whereby the valve I2 is moved to its intermediate position will now be explained. when the valve I2 is understood as the description proceeds. In the .7 fully opened. fluid-pressure .irom. portion SI. 0!

asraeee conduit 58 passes through openings I04. hollow portion I! of rod 12, openings I02 and into the inside of cylinder 90. Because piston 08 is of larger diameter than piston 16, the force exerted by piston 88 to cause rod 12 and valve I2 to'rnove toward the closed position will be greater than the force on the upper surface of piston I8 tend- 7 ing to hold valve It in the open position. This net force together with the action of springs 92 and 82 will cause the valve to move towards the closed position. Such movement will be arrested when piston 88 engages the shoulder 0| of cylinder 00. The pressure from portion 59 of auxiliary conduit 58, hearing against the upper surface of piston I8, will be suflicient to maintain valve I! in its partially opened or intermediate position at a clearance distance equal to the normal clearance between the upper surface of piston 88 and the lower surface of capping member 86. The valve I2 will remain in this position so long as normal fluid pressure exists on the upper side of piston I8,

The pressure fluid allowed to pass through conduit I4 to circuit breaker I8, after the arc has been interrupted need be maintained only so long as may be necessary for the series connected isolatingswitch to assume a safe isolating position. When the isolating switch has assumed such a position, it is desirable to permit the circuit breaker I8 to close in again under the action of biasing springs 84 and 38 in order that needless waste of pressure fluid from reservoir I0 may be avoided. To this end valve I2 is, of course, allowedto assume its fully closed position. To cause valve I2 to move from its intermediate position to its closed position it is only necessary, in accordance with my invention, to close the pilot valve 53; and thereby to shut off the supply of fluid from reservoir I0. When plug member 52 of valve 53 is moved clockwise under the action of biasing spring 50, fluid pressure within the cylinder l8 and above piston I8, is allowed to escape to atmosphere through portion 59 of conduit 58, and exhaust vent 55 of pilot valve 53. Biasing spring 82 will then force piston is and rod I2 upwardly so as to cause capping member 98 to become disengaged from piston 88 by a suitable normal clearance distance such as is indicated in the drawing. This upward motion of rod 12 will be suiilcient to cause valve I2 to reach its fully closed position therehv shutting off further supply of fluid from reservoir I0 through conduit It to circuit breaker I8.

It will be observed that when the main valve I2 is closed, any fluid pressure which may exist withinfthe cylinder 90, and below the piston 88, will be.-allowed to escape to atmosphere through the ports 93 in piston 08 because of the clearance distance between piston 88 and capping member 86. It; will also be observed that atmospheric pressure only may exist within cylinder 18 and belowpiston I6 because of the communication throughport88 to atmosphere. The mechanism 80 is, therefore, automatically readied for a new cycle} of performance.

Fig. 2 represents a modification of my invention wherein like parts are represented by the same numerals as those used in connection with the device of Fig. 1. The device of Fig. 2 performs in a manner similar to the performance of the device of Fig. 1 in that the device of Fig. 2 provides for an initial inrush of pressure fluid to the breaker followed by a reduction in the quantity and pressure of fluid for the purpose of conserving fluid from tank I0.

In the device of Fig. 2 the numeral I08 designates a piston slidably mounted in a cylinder I I0. The numeral II2 represents a biasing spring for the iston I08, rod I2 and valve I2 which spring serves to bias valve I2 to the closed position. The number H4 represents a conduit for supplying fluid pressure to the underside of piston I08 while the numeral I I8 represents a small fluid reservoir. A port H8 is provided in the wall of cylinder H0 and is located at a point intermediate the limits of travel of piston I08 for the purpose of determining the intermediate position of valve I2 as will be better understood as the description proceeds.

In order for the device of Fig. 2 to cause the valve I2 to assume its fully opened position, the valve 58 is opened in any suitable manner such as described in connection with the device in Fig. l. Fluid pressure then flows from reservoir I0, conduit 58, portion 58 of, conduit 88, and into the cylinder IIO above piston I08. This fluid pressure within cylinder IIO will operate to force piston I08, rod 12 and valve I2 downwardly to the fully opened position of valve I2 and the maximum flow of fluid will be allowed to enter circuit breaker I8 through conduit I4. The shoulder II8 within cylinder IIO serves as a limiting stop and determines the lower-most position of piston I08. After pilot valve 53 is opened, fluid pressure enters conduit I I4 which may be of smaller cross sectional area than conduit 58. Because of the smaller cross sectional area of conduit Ill, the rate of flow of fluid therethrough will be less than the rate of flow of fluid through portion 59 of conduit 58 and hence the build-up of pressure within cylinder H0, below piston I08, will be less rapid than the build-up of pressure above piston I08. In this way initial downward movement of piston I08, and opening of valve I2, is accomplished. The relative sizes of conduit Ill and portion 58 of conduit 58 as well as the size of spring II2 are preferably chosen to permit valve I2 to remain in its fully opened position until after the are drawn between retractable contacts 30 and 32 has been extinguished. After extinguishment of the are drawn between contacts 30 and 32, sufficient pressure builds up within cylinder IIO below piston I08 which together with the force of spring H2 will cause piston I08, rod I2 and valve I2 to move upwardly until piston I08 uncovers bleed port H8, at which time some of the pressure below piston I08 will be allowed to escape to atmosphere and a condition of equilibrium for piston I08 will result when pressure above that piston balances the total valve closing force comprising the fluid pressure below the piston and the force exerted by the spring II2. This condition of equilibrium will correspond to an intermediate position for valve I2 and will, therefore, result in a. substantial reduction in the amount of fluid supplied through conduit I4 to circuit breaker I8 from reservoir I0; The cross sectional areas of conduit 58 and the portion 59 thereof as well as the cross sectional area of conduit Ill and the size of spring II2 together with the location oi. bleed port H8 will be chosen to cause piston I08 and valve I2 to assume the proper intermediate position. It may be desirable further to delay the build-up of pressure within cylinder H0 and below piston I08 by the insertion in conduit Ill of a relatively small reservoir such as that indicated by the numeral II8.

In order to cause the valve I2 to move from its partially opened or intermediate position to the bleed port H8 which is uncovered as soon as v the piston I" moves a short distance toward the valve closed position. The piston Hi8 moves to its uppermost position under the bias spring I I2. fl'hus the device is quickly and automatically prepared for a succeeding cycle of operation.

It will be apparent to those skilled in the art that my invention is not limited to the particular construction shown but that changes and modiflcations may be made without departing trom the spirit and scope 01 my invention and I intend in the appended claims to cover all such changes and modifications.

What I claim as new and desire to secure by Letters Patent. of the United States is:

1..A mechanism torcontrolling the flow of fluid from a source of fluid under pressure to an'eleotric circuit breaker comprising a main valve operative to opened, closed and intermediate positions, a rod operatively connected to said main valve at one end and having a projection at the other end, a cylinder through which said rod is movable axially, a first piston secured to said rod and slidable in said cylinder in response to fluid pressure from said source to move said main valve to its fully opened position, spring means for biasing said first piston and main valve to the closed position, a second piston which. is spring biased toward the projection on said rod and slidably mounted there'- on and disposed within said cylinder, a. partition in said cylinder interposed between said pistons and dividing said cylinder into two chambers, an opening in said partition through which said rod is slidable, and means including'ports on said rod for establishing communication between said chambers at a predetermined position of said main valve after the initiation of the opening movement thereof, whereby said main valve is moved to its intermediate position by pressure fluid acting on said second piston and by the action of the biasing springs.

2. A mechanism for controlling the flow oi? fluid from a source of fluid under pressure to an electric circuit breaker comprising a main valve which is spring biased to closed position and operative to opened, closed and intermediate positions, a piston operatively connected to main valve, a cylinder for said piston, a conduit interposed between said source and said cylinder for supplying fluid to one side of said piston to cause said main valve to assume its fully opened position, a second piston and cylinder associated with said first piston and operative to move said main valve toward its closed. position. an auxil iary valve interposed between said source and said second cylinder and operative at a predetermined time after initiation of the opening movement of said main valve for supplying fluid under pressure to one side of said second piston to cause said main valve to move to its intermediate position, and an adjustable member disposed in the path of fluid flowing through said auxiliary valve tor regulating the time required tor the main valve to move irom its fully opened position to its intermediate position.

3. A mechanism for controlling the flow o2 fluid from a source of fluid under pressure to an electric circuit breaker, comprising a main valve which is spring biased to closed position and operative to opened, closed and intermediate positions, a piston operatively connected to said main valve, a cylinder for said piston, a conduit interposed between said source and said cylinder for supplying fluid to one side 01 said piston to cause said main valve to assume its fully opened position, an openin in said cylinder tor preventing the build-up of pressure on the other side or said piston, a second piston and cylinder operative to move said main valve toward its closed position. and an auxiliary valve interposed between said source and said second cylinder and operative at a predetermined time aiter initiation of the opening movement of said main valve for supplying fluid under pressure to one side of said second piston initially to provide a cushioned stop for said second piston and thereafter to cause said main valve to move to its intermediate position.

4. A mechanism for controlling the flow of fluid from a source of fluid under pressure to an electric circuit breaker comprising a main valve which is spring biased to closed position and operative to opened, closed and intermediate positions, a rod operatively connected to said main valve at one end and having a projection at the other end, a cylinder through which said rod is movable axially, a flrst piston secured to said rod and slidable in said cylinder in response to fluid pressure from said source to move said main valve to its fully opened position, spring means for biasing said first piston and valve to the closed position, a second piston which is spring biased toward the projection on said rod and slidably mounted thereon and disposed within said cylinder, a partition in said cylinder interposed between said pistons and dividing said cylinder into two chambers, an

opening in said partition through which said rod. is slidable, and means including ports on said rod for establishing communication between said chambers after the initiation of the opening movement of said main valve for tting fluid pressure to one side of said secondpiston to aid such piston and the biasing springs of both pistons in moving said rod and said :u; H. valve to the intermediate position.

5. A mechanism for controlling the flow o! fluid from a source of fluid under pressure to an electric circuit breaker comprising a main valve which is operative to opened, closed and intermediate positions, a rod operatively connected to said main valve at one end and having a projection at the other end, a cylinder through which said rod is movable axially, a first piston secured to said rod and slidable in said cylinder in response to fluid pressure from said source to move said main valve to its fully opened position, a second piston of larger diameter than said first piston and slidably mounted on said rod within said cylinder, a partition in said cylinder interposed between said pistons and dividing said cylinder into two chambers, an opening in said partition through which said rod is slidable, and means including ports on said rod for establishing communication between said chambers after the initiation of the opening movement of said main valve whereby fluid pressure is admitted to one side of said second piston to 9 cause such piston to exert a force against said projection sufficient to move said main valve to the intermediate position.

6. A mechanism for controlling the flow of fluid from a source of fluid under pressure to an electric circuit breaker comprising a main valve which is spring biased to closed position and operative to opened, closed, and intermediate positions, a piston operatively associated with said main valve, a cylinder for said piston, a first conduit interposed between said source and said cylinder for supplying fluid to one side of said piston to cause said main valve to assume its fully opened position, means including a second conduit of smaller cross-sectional area than said first conduit for supplying fluid to the other side of said piston to cause said piston to move toward its intermediate position at a predetermined time after said valve has occupied its fully opened position, and a port in said cylinder for venting the fluid from said second conduit to atmosphere upon being uncovered by said piston, said port being positioned to determine the intermediate position of said piston and said main valve.

7. A mechanism for controlling the flow of fluid from a source of fluid under pressure to an electric circuit breaker comprising a main valve which is spring biased to closed position and operative to opened, closed, and intermediate positions, a piston operatively associated with said main valve, a cylinder for said piston, a first conduit interposed between said source and said cylinder for supplying fluid to one side or said piston to cause said main valve to assume its fully opened position, a second conduit for supplying fluid to the other side of said piston to cause said main valve to move toward its closed position, a reservoir in said second conduit for delaying the build-up of fluid pressure on said other 40 .10 after said valve has moved to its opened position, and a port in said cylinder for venting the fluid from said second conduit to atmosphere, said port being positioned to determine the intermediate position of said piston and said main valve.

8. A fluid-actuated operating mechanism comprising a cylinder, piston means in said cylinder, biasing means normally restraining said piston means in one position, means including valve means for supplying fluid pressure to one surface of said piston means to cause movement thereof to an operated position against the action of said biasing means, fluid pressure control means for admitting fluid pressure from said valve means to another surface of said piston means during movement of said pistdn means toward its operated position, the build-up of pressure at said another surface being efiective together with said biasing means to move said piston means toward its normal position, means for arresting said last-mentioned movement of said piston means in an intermediate position, said biasing means being efiective to return said piston means to its normal position when the supply of fluid pressure to said piston is cut off.

JULIUS W. TIMMERMAN, J R.

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

UNITED STATES PATENTS Germany Oct. 14, 1937

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