US2238567A - Circuit breaker - Google Patents

Description

April 15, 1941.

D. C. PRINCE CIRCUIT BREAKER Filed Jan. 19, 1940 2 Sheets-Sheet l David C. Prince,

y AJM by Hi; Attorrweg.

April 15, 1941 D. c. PRINCE 2,238,567

CIRCUIT BREAKER Inventor: David C. Frye,

His Attorney Patented Apr. 15, 1941 UNITED STATES PATENT OFFICE CIRCUIT BBEAKEB David C. Prince, Swarthmore, la., assigner to i General Electric Company, a corporation of New York My invention relates to circuit breakers and more particularly to high-speed huid-operated circuit breakers.

In many high-voltage installations,- it is desirable to obtain higher speeds of opening of circuit breakers than has heretofore been possible. Circuit breakers have been designed which operate by spring pressure but, where high-speed tripping is desired, the mass of the springs becomes an important factor both in the amount of energy delivered to the moving parts and the rate of such delivery. In order to deliver sumcient energy, the springs must be heavy and, therefore, the inertia of the actual spring parts prevents any considerable amount of energy from being delivered by the spring in a very short time of the order in which it is desirable to operate a very high-speed circuit breaker. For this reason, air'or other fluid under pressure has been suggested as the operating force since' it passes a very large amount of energy with a negligible inertia. s

In fluid-operated circuit breakers, the fluid under pressure is usually supplied through extended pipes and controlled 'by a number of small valves. Because of this arrangement, there is a loss of pressure through the extended pipes, causing a delay insofar as high-speed operation is concerned and, furthermore, the time of operating the valve becomes considerable in very highspeed circuit breakers. In accordance with my invention, I provide an arrangement wherein the fluid for operating the circuit breaker is under pressure at the point where it is needed to open the breaker immediately in case of abnormal current conditions or other reasons without the delay caused by pressure loss due to the ow of the iluid through extended pipes as well as the delay coincidental with the operating of various valves. Ii my invention is applied to a breaker of the fluid-blast type, such as is disclosed and claimed in United States Letters Patent No. 1,898,900 granted February 2l, 1933, upon an application of Sigwart Ruppel, the fluid under pressure is also immediately available for the fluid blast for arc-extinguishing purposes.

Furthermore, when the operation of a fluidcontrolled circuit breaker is dependent upon the operation of a number of small valves which usually contain passages easily blocked by ice formed in cold weather from the condensation, a material question as to reliability arises. In my invention, on the other hand, these small valves operate only when the" circuit breaker is moved to its closed position and the openingof the circuit breaker is in no way dependent upon them but rather is dependent upon fluid under.

pressure which is always ready at the point of use and which may supply an appreciable amount of energy in a very short time due to the negligible inertia. l

Accordingly. it is an object of my invention to provide a new and improved fluid-operated high- 5 speed circuit breaker.

IIt is another object of my invention to provide a high-speed duid-operated circuit breaker in which fluid under pressure for .opening the circuit breaker is independent of the operation of valves or other apparatus which are likely to cause appreciable delay.

It is a further object of my invention to provide a fluid-operated circuit breaker of higher speed than has heretofore been possible and l5 which is reliable under all conditions of operation. j Further objects and advantages of my invention will become apparent as the following description proceeds and the features of Anovelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

My invention will be better understood from the following description taken in connection with the accompanying drawings in which Fig. 1

"- art that `my invention isalso applicable to other types of circuit breakers. The circuit breaker of Fig. 1 is illustrated as including a pair of relatively movable electrodes or contacts comprising stationary electrode III of the female type and movable electrode Ii of the male type. A double acting piston I2, operatively connected by means of connecting rod I3 to movable electrode Il, is arranged to actuate contact Ii when subjected to pressure fromuid pressure source I 4.

lindrical 'fluid-tight container Il, comprising a plurality of individual parts which will be hercinafter described, and is suitably supported on a base, not shown, by means of brackets of the type illustrated at l.

More speciilcally, electrode I0 of the female type is mounted at the upper end of cylindrical duid-tight container I5 which is provided with a nozzle-.like opening I1 for the escape of arc products during the opening or closing operations of the circuit breaker. Stationary electrode l0 comprises a cylindrical body built of separate sections I8 biased to form a tight nt with movable electrode il by means of suitable springs I9 mounted in a cylindrical conducting chamber 20 The entire circuit breaker is mounted within a cyorming the upper part of cylindrical casing i5. One of the power lines 2l is suitably connected to cylindrical conducting member d, and, hence, also to stationary electrode lit. The lower end. oi' cylindrical member 2@ is provided with a streamlined por-tion 22' forming a suitable valve seat for fluid-blast valve 23 carried by movable electrode il and connecting rod lil. 'The entire unit, including stationary electrode lli, cylindrical member 2li, and streamlined valve seat 22, is mounted upon a suitable insulator alii forming another part oi cylindrical fluid-tight container l5. Suitable packing material 25-and 26 is-provided at either end of insulator 2li to prevent the escape of iiuid under pressure contained within Jduid-tight container l5. The other power line 2i? is connected to a conducting cylindrical niember 2d interposed between insulator 2Q and insulator 29, all forming part of cylindrical :duida tight container t5. Electrical connection between movable contact il and power line 2l is provided through a conducting portion lil of connecting rod i3 and a plurality oi' conducting segments 30 iiexibly mounted on springs 3l attached to conducting cylindrical member 28, which provide the necessary contact pressure between seg ments 30 and yconducting portion i3' of connect Ing rod i3. j

The operating mechanlsmof circuit breaker I is insulated from the highdension portions of the circuit breaker by insulator 2Q and an in-s sulating' section i3 of connecting rod i3. Pis= ton I2 is arranged'to operate in cylinder 32 and is operatively connected to connecting rod lil associated with movable contact il by means of a sliding joint comprising a tube 33 telescoped with a reduced section 34 of rod 34 including a slot 35 cooperating with pin 36 fixed in tube This sliding joint is included in order to provide suitable sealing of valve 23 in spite of the back lash unavoldably present in the latch mechanism described hereinafter which sealing is produced by virtue of spring 3l mounted between tube 33 and the enlarged portion of rod 34. Rod 34 and the sliding joint all form. part of connecting rod i3. Cylinder 32 is connected to insulator 29 by a suitable cylindrical Ymember 38, and members 20, 24, 28, 23, 38, and cylinder 32` together form the cylindrical :duid-tight container I for the circuit breaker. Rod i3d forming part of connecting rod i3 is operatively connected to the upper side of double-acting piston l2 while a rod 39 is connected to the lower side of piston l2 and extends beyond the lower end of cylinder 32 through an opening Gil in end cover 4I closing the lower end of iluid-tight cylindrical container I5. A suitable gland t2 is provided for rod 39 to prevent the leakage of any :duid from the lower end of cylinder 32 while still allowing the -reciprocation of rod 39 in accord ance with the movements of piston l2. i

An overcenter device 43 is provided in order to releasably latch the circuit breaker in the closed position and comprises a toggle arrangement including bell crank 44 pivotally mounted at 45 to the lower end of cylindrical duid-tight casing I5. One end of bell crank 44 is provided with a U-shaped notch 46 which cooperates with roller 41 attached to the end of rod 39 associated with piston I2. The other end of bell crank 44 is pivotally connected to oneend 'of a toggle comprising .links 48 and 49, the other end of the toggle being connected to a fixed pivot 50. Link 49 is provided with an extension. 5I adapted to cooperate with a pin 52 attached to bell crank de. in the arrangement shown with extension bl engaging with pin t2, the toggle comprising links il@ and il? is in the overcenter position so source it which may, for example, be a sourcel of air or other suitable gas under pressure with the lower end of cylinder 32 so as to operate against the underside of piston l2. in another operating position ci closing valve 53, the lower end of cylinder 32 is vented to atmosphere. A pressure-balanced valve 5b is provided for connecting the-upper end of cylinder 32 and the remainder of the cylindrical :duid-tight con tainer lb with the source oi fluid under pressure 84 both for opening the circuit breaker and also for supplying the iiuid for the iluid blast when uid=blast valve 23 is open whereby an arc drawn betweencontacts l@ and il is extinguished. Balancedgpressure valve 55 comprises a piston 56 cp- !eratively connected to a valve member 5l which cooperates with valve seat 58. Piston 56 is mounted within a cylinder 59 bolted to the side of cylindrical gas-tight casing I5 adjacentvalve seat 58. A spring means 60 biases the balancedpressure valve 55 to the closed position. Under isteady-state conditions, the fluid pressure acting on piston P56 is balanced on both ends of the piston by virtue of a small opening 6I, somewhat exaggerated in the drawings for purposes of illustration, which allows an equalization of pressure. In order that balanced-pressure valve 55 may be operated to the open position against the bias (if-spring means di), l provide a pilot valve 62 which provides a large opening relative to opening 6I for interconnecting the respective ends of cylinder 59 so that the pressure operating on both ends o! piston 58 may be unbalanced. Pilot y valve 62 is normally biased to the closed position by means of spring $3.

In order to operate balanced-pressure valve 55 at a predetermined position of movable electrode il during the circuit-closing operation, I

provide cam 64 associated with connecting rod B3. A pivotally mounted member 65 provided with rollers 66 is engaged by cam 64 just before the closed position of the circuit breaker is reached so as to engage the end of pilot valve 62 and move it to the open position, as shown in Fig. l. Tile opening of pilot valve 52 immediately releases the pressure on the right-hand end of piston Bi whereby the pressure on the lefthand end is sumcient to overzyrlie the force of spring means 60 whereby balanced-pressure valve 55 is opened. A cuplike member 61 forming part of pilot valve 52 adjacent `pivotally mounted member 65 is provided so that cam 64 maintains balanced-pressure valve 55 in the open position whenever the circuit breaker is in the closed o position. Bythis arrangement, cylindrical iiuidtight casing I5 is maintained under pressure when the circuit breaker is closed so that, whenever overcenter device 43 is released, fluid under pressure is immediately available to move piston I2 downwardly, thereby opening the circuit breaker and, furthermore, iiuid under pressure for ilud blast purposes is also available `to extinguish the for thearc drawn. between electrodes I and II when gas-blast valve 23 is opened It will be understood :that any well-known control means may be provided for operating the circuit breaker illustrated in Fig. 1. Accordingly, I have illustrated afsource of potential 68 for energizing the manually controlled tripping and closing circuits of the circuit breaker. A closing switch 68 is provided for connecting solenoid 54 associated with valve 53 across potential source 68 through contacts 10 of a pressure-operated relay 1I. Pressure-operated relay II is connected with cylindrical fluid-tight casing I above piston I2 through a suitable tube 'I2 and comprises a bellows 'I3 which is arranged to expand when iluid under pressure is allowed to enter chamber I5 thereby opening contacts 'I0 which are normallyclosed when the pressure within chamber I5 is released. Close switch 88 is adapted to be manually operated and is provided with a dashpot 69' in order to delay the opening thereof to insure the closing of the circuit breaker. It will be understood by those skilled in the art that switch 58 could be replaced by the conven-` tional push button switch with seal-in contacts to insure the closing of the circuit breaker. The tripping of. the circuit breaker is accomplished by solenoid 'I4 which has one winding, 15 thereof energized from potential source 68 through trip button 13. f Solenoid 14 has a pin-like extension 'I1 which is adapted to strike one oi' the links 48 or 48 of the overcenter device so as to allow tripping of the circuit breaker. A second winding 18 is provided forsolenoid I4 which is connected to a current transformer 'I8 associated with power line 21 so that ltripping of the circuit breaker is obtained when abnormal current conditions occur in the power lines.

'I'he operation of myl circuit breaker will be considered iirst with reference to the closed position of the circuit breaker as shown in Fig. l. overcenter device 43 is in such a Aposition to mechanically restrain or latch movable contact H in current-conducting relation with fixed contact III while, at lthe same time, maintain blast valve 23 against streamlined valve seat 22. Balanced pressure valve 55 is held open by cam 64 and pivotally mounted member 35 so :that uid under pressurefrom source I4 completely lls cylindrical iluid-tight casing I5 above piston I2 and below gas-blast valve 23. This fluid, of course, is immediately available independently of the operation of any valves or the like for opening the circuit breaker and providing the arc-extinguishing uid blast when the mechanical restraining means comprising overcenter 'device 43 is tripped. Furthermore this fluid under pressure in chamber I5 expands bellows I3 thereby opening contact I0 and preventing the operation of solenoidoperated valve 53 when the circuit breaker is in the closed position. If an overload should occur on the power lines associated with the circuit breaker or if it were desired to manually trip the circuit breaker, solenoid 14 would be energized through coils I8 or 'I5 respectively, whereby overcenter'devlce 43 would be tripped and the restraining force holding the circuit breaker in the closed position would be removed. soon Y as this tripping occurs, the uid under pressure against the upper side oi piston I2 would immediately force piston I2 downwardly and this,

vide the necessary fluid blast for arc extinguishment the instant overcenter device 43 is released. Opening of the circuit breaker allows pilot valve 62 to close and furthermore iiuidpressure valve 55 moves to the closed position as soon as the pressures are balanced so that spring again obtains control. Air or other gas or iluid in cylinder 32 below piston I2 is Vented to atmosphere through valve 53 during the opening operation of the circuit breaker.

To close the circuit breaker, switch 69 is operated the opening of which is retarded by dashpot 68. Contact I0 had been closed since the fluid pressure in cylindrical uid-tight chamber I5 wasreleased through blast valve 23. Therefore, the closing of switch 69 energizes solenoid 54 allowing iluid under pressure from source I4 to enter the lower end of cylinder 32 forcing piston I 2 upwardly and moving contact I l toward stationary contact Ill. As soon as cam 'B4 engages with pivotally mounted member pilot valve 82 is opened and the pressure on the righthand end of piston 58 is released so that balanced-pressure valve 55 is forced open and held open by cam 64, pivotally mounted member 65, and cup-shaped member 61 associated with pilot valve 52. A blast 0f fluid or air is allowed to pass through blast valve 23 vprior to closing thereof to prevent the'formation of an arc before the circuit breaker is closed.

In Fig. 2, I have illustrated a modification of my invention wherein the mechanically operated pilot valve 32 is replaced by an electrically opermovement would open blast 'valve 23.V Very high speed operation of the circuit breaker is thereby obtained since the fluid under pressure is available to move piston I2 downwardly and to` pro-fVA ated' pilot valve. 'Ihe corresponding parts of the circuit breaker illustrated in Fig. '2 are designated by .the4 same reference numerals as in Fig. 1. Balanced-pressure valve -55 is provided with a solenoid-operated pilot valve normally biased to the closed position by means of spring 8l. In order that this valve may be operated at a predetermined point in the closing stroke of the circuit breaker, a cam 82 is lprovided connected with rod 34 of connecting rod I3 for causing the engagement of contacts 83 connected in an electrical circuit for energizing `the winding 84 of solenoid-operated pilot valve 80 from source of potential 58. By this arrangmenhlpilot valve 80 is electrically operated atv a predetermined point in the closing stroke of the circuit breaker causing operation of balanced-pressure valve 55 in` the same manner as in Fig. l. In order to hold valve member 51 of balanced-pressure val! e` 55 in the open" positionv when the circuit breaker is closed, I provide a vane-operated membery 85 pivotally mounted at 86 and biased to the posi-` tion shown in Fig. 2 by spring means 81. 'This member 85 is provided with a vane 88 arranged 1 anced-pressure valve 55 forces vane 88 to rotate about pivot 88 whereby member 89 releases valve lmember 51 and allows closure. of balanced-pressure valve 55 to take place. Pressure relay 'II is arranged so as to break the circuit of solenoid- I operated pilot valve 88 after the circuit .breaker hasvbeenA closed. The operation of the arrangement illustrated in Fig. 2 will beunderstood by those skilled iny the artin view*l of the detaileddescription set forth in connection with Fig. l1.

, While l have shownparticular embodiments of.'

my invention as applied to a fluid-operated circuit breaker of the gas-blast type, it will be ap-s parent to those skilled in the art that my invention is not limited to the particular construction shown but that changes and modifications may be made without departing from the spirit and scope of my invention and l aim in the lappended claims to cover al1 such changes and modifications.

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

1. In a fluid pressure operated circuit breaker, the combination comprising a plurality of relatively movable electrodes, fluid-operated means associated with one of said electrodes for producing relative movement between said electrodes, a source of fluid under pressure, means for connecting said first mentioned means and said source of uid when said circuit breaker is in the closed position so that said fluid under Vpressure constantly tends to open said circuit breaker, means for restraining said circuit breaker in said closed position, and means for tripping said last mentioned means, whereby said source of fluid under pressure is released to operate said first mentioned means. l

2. In a fluid pressure operated circuit breaker, the combination comprising a plurality of relatively movable electrodes. fluid-operated means associated with one of said electrodes for producing relative movement between said electrodes, a source of fluid under pressure, said source of fluid under pressure constantly tend ing to produce relative movement between said electrodes when said .circuit breaker is in the closed position, means for restraining said circuit breaker in said closed position, and means for tripping said last mentioned means, whereby said source of uid under pressure is released to operate said first mentioned means.

3. In a fluid pressure operated circuit breaker, the combination comprising a plurality of rielatively movable electrodes, fluid-operated means associated with one of said electrodes for pro-l ducing relative movement between said electrodes, a source of fluid under pressure, means for connecting said first mentioned means and said source of fluid when said circuit breaker is in the closed position so that said iluid under pressure constantly tends to open said circuit breaker, means for restraining said circuit breaker in said closed position, means for tripping said last mentioned means, whereby said source of fluid under pressure is released to oper ate said first mentioned means, and means :tor

. connecting said first mentioned means and said source of fluid to operate said circuit breaker to the closed position.

4. In a fluid pressure operated circuit breaker, a plurality of relatively movable electrodes, duid operated means associated withl one of said electrodes constantly tending to produce relative movement between said electrodes, means for latching said circuit breaker in the circuit-closing position, and means for tripping said lastmentioned means so that said first-mentioned means is caused to operate independently of the operation of valves, thereby producing high speed opening of said circuit breaker.

5. In a fluid pressure operated circuit breaker, a plurality of relatively movable electrodes, uidoperated means associated with one of said elec trodes for producing relative movement between said electrodes, a source oi fluid under pressure,

said source of fluid under prmsure constantly 75 arcate? tending to produce relative movement between said electrodesv when said circuit breaker is in the closed position, means for restraining said circuit breaker in said closed position, means for releasing said last-mentioned means whereby said source of fluid under pressure ls released to operate said first-mentioned means, and a blast valve for releasing some of said fluid under pressure to extinguish any arc drawn between said relatively movable electrodes when said restraining means has been tripped.

6. In a fluid pressure operated` circuit breaker, the combination comprising a. plurality of relatively movable electrodes, a fluid tight casing including a cylinder, a piston reciprocally mounted in said cylinder, a connecting rod interconnecting said piston and one of said electrodes so that relative movement between said electrodes may be obtained, a source of fluid under pressure, a valve for connecting said source of fluid under pressure with said fluid tight casing and one end of said cylinder so that said fluid may operate on said piston to open said circuit breaker, a second valve for connecting said source of fluid with the other end of said cylinder to force said circuit breaker to the closed position, a blast valve operated by said piston, cam means associated with said connecting rod for opening said first-mentioned valve at a predetermined point in the closing stroke of said circuit breaker prior to the closing of said blast valve so a blast of fluid may escape through said blast valve, means for latching said circuit breaker in the closed position, and means for holding said firstmentioned valve .in the open positionv while the circuit breaker is in the closed position so that said source of fluid under pressure is continually ready to open said circuit breaker and provide a fluid blast through said blast valve whenever said latching means ls released.

7. In an electric circuit breaker, the combination comprising a plurality of relatively movable electrodes. a connecting rod associated with one of said electrodes, means for, operating said connecting rod to produce relative movement between said electrodes, a blast valve mounted on said connecting rod adjacent said electrodes, and a source of fluid under pressure restrained by said blast valve when said circuit breaker is in the closed position, said fluid under pressure being released upon opening of said circuit breaker and consequent opening oi said blast valve to produce a fluid blast for arc-extinguishing purposes.

d. In an electric circuit breaker, the combination comprising a pluralityof relatively movable electrodes, a casing, a connecting rod associated with one of said electrodes and arranged to operate within said casing, means for operating said connecting rod to "produce relative movement between said electrodes, a blast valvev operated' by said connecting rod for closing one end of said casing, a source of fluid under pressure, and a second valve operated by said connecting rod ata predetermined point in the operating stroke of said circuit breaker for releasing said source of fluid under pressure into said casing, said second valve being mechanically held in the open position whenever said circuit breaker andblast valve are in their closed positions, whereby said blast valve releases said fluid under pressure in said casing to produce an arc-extinguishing blast of fluid upon opening of said circuit breaker.

DAVID C. PRINCE.

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