US2611846A - Circuit breaker - Google Patents

Description

L. M. APPLEGATE Sept. 23, 1952 CIRCUIT BREAKER Filed March '7, 1949 INVENTOR.

Patented Sept. 23, 1952 UNITED STATES PATENT OFFICELJ-"jfi CIRCUIT BREAKER Lindsay M. Applegate, Oswego, Oreg., assigner to the United States of America as represented by the Secretary vof the Interior y Application March 7, 1949, Serial No. 80,051

9 claims. (ci. 20o-144) s (Granted under lthe act of March', 1883, .as

l l The invention described hereinmay be manufactured and used by or for the Government of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (Ch. 460, 45 Stat. L. 467).

This inventionrelates to circuit breakers intended for interrupting currents in high voltage transmission systems. It is well known in this art that the dielectric strengths of gases increase with pressure. This is applied inexisting circuit breakers byQconiining arcs in oil-lled chambers wherein the arc produces gas by heating the oil thus developing pressures of the order of 100 atmospheres for short periods of time toassist in quenching the arc and interrupting the current. Inother circuit breakers air under pressure yof the order of 10 vatmospheres isjdirected through or on contacts while being separated for the combined purposes of cooling the arc, blowing away ionized gas'. and increasing dielectric strength of the arc path. It is known also in rthis art that extinguishing arcs iny circuit breakers is facilitated .by the use of heavy `I`metal parts capableofconducting heat away from the arc thus-assisting in deionizing the gasesy near the surface of the metal. Another principle known and used in vthis art is that of rapidly opening the arcing gap to build up, as rapidly as possible, the dielectric strength of the arc path in the circuit breaker. In addition, the number and variety of kinds of operating mechanism in circuit breakers include pneunlatic, asf welll as spring, motor, solenoid and other'motivating'systems.. These. fundamentals of circuit 'breaker construction have been applied in many different ways,]andI although some ofthese same fundamental principles are used in my` present'in'vention, the way they are appliedinthis instance accomplishes some useful objects in a novel way. The principal object of my present invention is to produce'a high voltage circuit breakerof simple construction for fast current interruption. Another object is to produce a circuit breaker of` this kind within relatively compact dimensions.y A third object `is to produce a good circuit breaker for high voltage that vdoes not have to usevk either oil or large volumes of gasfor arc quenching. l j; v y n j u yWhat `constitutes this, my present invention, is shown in thejaccoinpanying drawing,y described inthe specification following land is succinctly de-.

ned in the appended claims. y i In theldrawingFigure 1^ is a generalfsche-`` matic longitudinal View of the' invention'in a amended April 30, 1928; 370 O. G. 757) ISU preferred form of embodiment. Figure 2 is a" sectional detail of apart ofthe structure shown in Figure 1. Figurev 3 is a View along the axis ofFigureZ. In Figure l, there areterminals I and ifconnected to the circuit to be controlled by' the circuit breaker by conductors 3 and 4. Terminal- I, referred to for convenience as the bottom ter-fi minal, is sealed intoa terminal or base platefi Attached to plate 5 there is a series of'insulaftirig. annular discs 6 (referred 'tofalsoas annuli-)'a'nd conducting annular discs 1.r Thesediscs 'are-fastened together by bolts 8 and 9 to`forrri a gash' tight hollow cylindrical chamb rf designated its entirety as chamber I. if", At the upper end of chamber 'Ill-ther closure II through which a plungeror enters the cylinder. Rod I2fis"offjhighly ducting metal and is arranged'tomak Contact with terminal I when in the closed position.l Rod I2 slides through terminal `2 which isfarf-f ranged to permit movement of rod, I2 and to carry the current appropriate to the ratingofI the circuit breaker. v .V Rod I2 is arrangedA to -move longitudinallyfto and from. terminal I approximately 4throug'l'i"the full length of chamber III. Actuation ofjrf'idfli.y may be by any convenient mechanical,arrange-v ment,4one preferredbeing a pneuniati'cy cylinder I3vand piston Iiiv attached to rod; l2. Clearance between rodr I2- and annular discs 'I is `provided. so that, allowing-'for the'iusual inaccuraciesof manufacture and of ordinary'deiiect'ions in 'op-` eration,rod I2 will not touch discs ,'Ifhisfre'-A quirement is not a fundamental one inasmuch as electrically rod I2 could slide on discs] with-.-1 out any change inr operational principle.v `.1If,jin circuit breakers requiring long travel ofrodIZ'; i t be desired to operate rod I2 in contact with' discs "i, provision should be made for smooth opera-A tion avoiding damage to theedges ofdiscs .TI-by rod I2 hitting the discs in closing..` To vavoid this, rod I2 should be slightly rounded at the periphery at the end. y

Wherevrod I2 'enters chamber I0, a\se"a1' .or stuiiingbox I5 is provided to preventfecessive gas leakage. Similarly where rod I2fenters cylin-V der I3 there is a seal or stulingfbox Iii. Either or both of these seals maybe omitted undersome arrangements of construction,..none of which ar vital tp the principles of operation of thecircuit breaker. lOne variation' of construction'is to combine terminal `2 and one or the other ffSeals I5.or I6 to, serve the ldual purpose of contactand seal. VvThese variations, however, are matters'of design. Rod I2 is drilled longitudinally to provide a central conduit 35 with lateral openings 20 at each end.

The assemblage of chamber I9 and cylinder I3 together with, the other parts is enclosed in a cylindrical porcelain insulator Il to protect the assemblage from the weather and to maintain a high degree of insulation over the outside of chamber I and to provide mechanical support. The space between chamber Ill and insulator I'I may be lled with an insulating compound such as oil to further provide forV good insulation. The space between chamber I0 and insulator II is not necessarily under pressure, inasmuch as the pressure is generally conneditoithe. interiorl of chamber I0 and cylinder I3.

Connected with chamber I0 and cylinder I3 there is a source of high-pressure gas, preferably hydrogen at pressures of 100 atmospheresor more represented by gas container I 8. This may be an ordinary;y tank of commercially compressed hydrogen or of other 'commercially available gases, ora locally'pumped supply of compressed air.

Container I8 is connected to chamber IU'and cylinder'A I3- throughv an assemblage of valves and electrically non-conducting tubing subject to considerablevariation in arrangement. In the arrangement shown in Figure l, gasI fromcontainerr I8-is admitted to chamber I0 through two paths' in parallel. The first path is through a regulating valve,f I6 which .normallyV holds aprescribed-pressureinsidechamber I9. The second path is through a magneticallyoperated valve 2I including 4anbperating coil 22, an inlet valve 23 and an outlet valve 24; Connected to outlet valve 24A-there is asecond-regulating valve25.

`(Lcntainer.IB-fis connected to cylinder` I3 throughf-amagnetically operated valve 26 including al1-operating coil-21, .aninlet valve 28, and` an outlet valve 29. Inlet valve 28 is connected tocontainer I8 through a regulatingl valve 30.

`Valves 2| and l26-are interlockedso that-one is open when the other is closed. Thiscan be donefinanyconvenient way, oneof which is accomplished Vby a double-throw switch 3|. In thegup' position` of the switch 3|V thehcircuit breaker isl opening.. and in the down .positionY the circuit. breaker is closing. p

.Figures 2 and 3v show` theY structuraldetail of thediscs Sand 'I together withI bolts 8 and.9 for 'providing a gas-tight chamber I0. Disc 6 is made of mechanically strongdielectriamaterialf'such as vulcanized nbre'or Bakelite. Disc 'I- is made of a metal, preferably of good heat conductivity such as copper. Disc 'I has a concentric'. hole somewhat larger than the diameter of rod I2. Disc 6 has a concentric hole considerably largerltha'n the hole vindisc 'I, and also a pluralityy of bolt holes .as indicatedV in Figure 3. Bolts 8 and 9 are put alternately in the positions indicated in Figure 3 so that thereis no continuousv bolt connection along chamber I0. Countersunk flat head bolts threaded into the mating discs `6 are preferred to provide maximum 4 heat of the arc inside chamber I0. The thickness of discs 6 is determined primarily by strength requirements. For example, if the rod I2 is 3 centimeters in diameter, the diameter of the hole in disc 1, allowing for necessary mechanical clearance, is ofthe order-.of 4 centimeters. This makes the outerdiameter of discs 1, for suitable mechanical stability, of the order of 12 centimeters. Adequate space around the periphery off discsT for bolting in discs 6 requires in this example about 4 centimeters, making the outside diameter. of discs 6 about 20 centimeters. The thickness:I of discs 6 for good mechanical construction' in a diameter of 20 centimeters requires'a thickness of the order of 2 centimeters.

Two centimeters spacing between discs 'I is, in` this example, sucient for accommodating prcjectionsdueY to heating at the edges of discs 1. The thickness of discs I should be comparable with the thickness of discs 6 to provide asmuch metal, facing the interior of chamber Illas practicable for the absorption of heat'duringl the Vperiod of arcing.

The spacing of bolts in Figure 3 is illustrative only; The actual spacingneeds to be small enoughto avoidbending in discs 6 when chamber IIIy is under pressure. The essential consideration in bolt arrangement, in addition to the necessary strength is that the bolting be rotated or 'staggered around discs 6 so that any one set of bolts extends across only a minimum of discs 1, preferably/only two, to avoid the occurrence of more voltage than necessary between adjacentsets of bolts. This assures a high insulating value from end to end of chamber I0 since by displacing bolts 8 and 9 an'gularly, the total insulationalong chamber I0 is practically that of airo'f the length of the cylinder sincefthe spacing betweenadjacent bolts can be'made as much asthe length of the bolt.

- Referring again to Figure 1', assume for purposes of explanation that the circuit breaker isi closed. Rod I2 is in contact with terminalI. Switch 3l has been closed downward thus energizing valve coil 21, opening valve 28, and closing valvel 29 tothe air. Regulating valve l3|! holds a predetermined pressure in the right hand end of cylinder I3 through an electrically nonconducting pipe 4I. Pressure on the right of piston I4has forced rod l2 into contact with terminal I. n

Under this breaker-closed situation gas under predetermined pressure .is admitted to chamber IIJ through regulating valve I9 and an electrically non-conducting pipe 33. The relationship of pressure provided by regulating valves I9'. and 39 is such that there will be a net dilerence in total pressures on the two sides of piston I4 andl rod I2 that is sufficient to hold rod I2 in contact with terminal I.

When the circuit breaker isv to be opened, switch 31| is thrown to close upward energizing coil 22 ofvalve 2l and. deenergizing coil 2'I of valve 26. `Valve 23 is opened admitting the full pressure of container- I8 through pipes 34 and 35 to pipe 33 and to the interior of chamber I0. Regulating valve I9 is arranged with a check valve or other one-way construction to permit more than the normally regulated pressure to exist in chamber I0 when valve 23 is opens Valve 24 is closed Aby. the action of coil 22 permitting the building up of full. pressure `in chamber I0. Pressure from chamber I0 is `communicatedto therleft hand end'of cylinder I3, through conduit. 36 drilled.lengthwisethrough. rod I2, put-v aci-1,346

tional method of damping the movement to avoid s hock'in stopping can be. used, for example the'A expedient 'of a dashpot space at'r the end of the cylinderas indicated at space 31 provided by putting the connection ofl pipe 32 an appreciable distancefrom the end of cylinder I3. When the piston 'I4 passes the end of pipe 32, the gas inthe space beyondin the end of cylinder I3 is com pressed and by escape past piston I4 provides suitable deceleration and damping. A similar expedient at the left end of cylinder I3' can be used, or the pressure of the gasvused for closing the circuit breaker can be limited byreducing valve 30 sufficiently to prevent unnecessarilyV heavy impact of rod I2 on terminal I in closing the circuit breaker. n

When valve 23 is closed and valve isopened after the circuit breakeropening just described, the high pressure that has been developed in cylinders I0 and I3 isV relieved through regulating.A Valve'ZWhich is set to hold a pressure somewhat greater than that maintained by regulating valve I9. This permits the pressure admitted by valve 28 and regulating valve 36 toy close the circuit breaker. i

There are many alternative methods of operatf ing rod I2 and of arranging the pneumatici systern. For example pressure can be admitted directly to the left end of cylinder I3 by a pipe 3,8,

shown dotted in Figure 1. Withthis arrange--k ment ypressure can be communicated to chamber I0 through conduit 36 in rod I2, but this has the disadvantage of lowering` the pressure somewhat in the reg-ion'of the initial break at terminal I due to drop in pressure through the conduit'e. Another alternative arrangement is `to have no communication between chamber I I) and cylinder I 3, using either a regulating valve and reduced pressure or the full tank pressure of' container I8 in chamber Ii) and providing entirely separate connections for cylinder I3. Cylinder I3 can be operated either by the gasv in container I8 or by anl entirely separate source of compressed gas. 'Ihe` important consideration'is to maintain high pressure in chamber IIJ throughout the time of the circuitbreaker opening and to providesufcient differential of pressure in cylinder I3 to assure rapid movement of rod I2. The pressure in chamber IG can be maintained at the full pressure of container I3 continuously if adequate separate operating means are provided for activating rod I2v independentlyof the pressure inv chamber I0. Alternatively the pressure 4in chamber Il) can be maintainedy at some lesser value or. at atmospheric pressure except Whenthe circuit is to be opened. An advantage of arrangements in which the pressure in chamber I0, when the circuit breaker is closed, remains less than the pressure when opening is that the sealing against loss of gas is not sofimpOrtant.

.Itis known in this art that the dielectric` strengths of gases under high pressures are much greater than at lower pressures .and further that gases at high pressures have dielectric strengths" greater than those of many insulating liquids.l

The increase in gas pressure develops the dielectric strength in a relatively small thickness of the gas. Accordingly pressures incharnber I0 of the order of atmospheres or more are preferred.` One of the important differences between my invention and the circuit breakers of the prior art'v is that a high pressure in the circuit interrupting chamber is provided before the contacts open.A This high pressure is thus effective from the beginning of the circuit breaker opening. In the prior art high pressures in enclosed chambers` resembling chamber ID are. produced by the heat developed in the arc between the contacts after they open.- The suppressionof thearc in such' arrangements does not occur until the arc has" existed long enough to develop considerable heat.'v When the pressure in yconventional circuit' breakers has developed sufficiently to interrupt the arc, the production of heatvceases and the pressure and dielectric strength of the gas de-"" crease. In some circumstances, if in such cire' cuit breakers the arc has been interrupted beforel the rcontacts have become much separated,v addi' tional arcs may occur, producing what are comel monly referred to as restrikes In my invention the presence of gas under high pressure from the"V beginning to the end of the arc opening process: causes the arc to be extinguished quicklyfan'd to minimize restrikes.`

It is known also in thisart that hydrogen has' properties favorable for use in the presenceof heat and arcing. Hydrogen avoids oxidation and` corrosion due to high temperature and has fthe desirability of conducting heat more readily than many other gases. Accordingly hydrogen is the gas preferred for use in chamber Iii.' Hydrogenv is preferred also because of being readily available at comparatively low cost in tanks at pressures;v

of 100 atmospheres or more.

In the normal operation of this invention very large currents traverse the arc between terminal;

I and the end of rod I2 for short periods of timer' and also through arcs between adjacent conducting annuli l. These arcs cause some of the metal of terminal I, rod I2, and annuli 'I to be vaporizedj The 'vaporized metal is carried by the movementl of the gas rin chamber IIJ tothe*coolerpartspfA the chamber where the metallic vapor is cori-jv densed to form a deposited layer of metal. In orderto minimize the deposition of metal on-they inner surfaces of insulatingjannuli 6, the dif-v ference in the diameters of the holes in annuli 6 and annuli I is made'as muchas is mecl'ianicall'yi convenient. The projection of annuli 1 in cham ber 1 I 0 appreciably within the inner radius of annuli ii, Vthereby presenting the maximum prac` ticable area of exposedconducting metal surface, tends to' collect a maximum amount of4 vaporized metal and to prevent deposition on the surfaces of annuli 6. In general in the dimensional rela-` tionship of annuli 6 and T, the conducting annuliIv 'I should be as' large as is feasible to provideth'el maximum possible amount of metal for `the ab,-k sorption of heat from the arc in chamber ID; The purpose of insulating annuli 6 is to provide 'insulation vbetween adjacent annuli 'I and to'. pro-A vide the necessary mechanical strength 'for as-- sembly. Accordingly annuli 6 should be restricted;

in internal dimensions and in thicknessto a de-= gree .consistent with. the minimum electrical in.-4

sulation andof mechanical strength required 'for'.y safev and reliable operation. e

The vgas that moves during the circuitbreaker' opening from chamber l through rod l2 into cylinder I3 is subjected to heat and ionization in chamber l0 and accordingly tends to cool chamber l il. This removal of heated and ionized gas continues after the circuit breaker has been fully opened until switch 3| is opened, closing valve 23. The additional gas blown through chamber li) and cylinder I3 does no harm and may contribute to circuit interruption but controls should be provided to prevent unnecessary waste of gas and loss of pressure in chamber iB. Conventional means for sequential control of valves are adequate for this.

In the mechanical arrangements for using this circuit breaker two units as shown in Figure 1 can be coupled Itogether at plate providing a double-break ycircuit breaker. Also this circuit breaker can be combined with other sets of contacts in parallel so that terminal l and rod I2 willcarry the full circuit current only at times of circuit opening or closing. The combination of heavy current carrying contacts which open before the operation of contacts specially designed for arc interruption is already known in this' art. My invention is adaptable for use in such multiple contact arrangements in place of the known arc interruping devices as well as to use in place of the ordinary oil or air circuit breakers.

I claim:

1. A high voltage circuit breaker comprising a chamber composed of a plurality of conducting annuli interspersed wi-th insulating annuli to form a gas tight insulated cylindrical chamber, separable contacts inside said chamber, and means for maintaining gas under pressure in said chamber said conducting annuli being held between said insulating annuli which are held in compression on said conducting annuli by bolts spaced .around the outside of, and separated from, said conducting annuli. y

2. A high Voltage circuit breaker comprising a chamber composed of conducting annuli intersperced with insulating annuli, the outside diameter of said insulating annuli being greater than that of the conducting annuli, bolts holding successive pairs of insulating annuli together, said bolts being angularly displaced around said annuli so bolts in successive pairs of annuli are insulated from each other thus providing a chamber bolted end to end in which said conducting annuli are insulated and in which the .end to end insulation of said chamber is comparable with the same length in air, separable contacts in said chamber and means for maintaining gas at high pressure therein.

3. A circuit breaker comprising a cylindrical chamber composed of alternate annuli of insulating and conducting material, bolts in said insulating annuli holding them together, said bolts staggered to provide secure holding wi-thout objectionable impairment of longitudinal insulation strength over said chamber, separable contacts in said 4chamber and means for maintaining an atmosphere of gas at high pressure in said chamber..

4. In a circuit breaker the combination of a xed contact, a movable contact and a pressure chamber comprising a stack of alternate conducting and insulating annuli and longitudinal bolts Yfor holding said annuli together to provide a gas-tight chamber insulated between the ends, saidvconducting annuli each having a smaller external diameter than said insulating annuli, andsaid bolts being spaced around successive pairs of said insulating annuli outside and separated from said conducting annuli, said spacing providing for bolts in any two successive insulating annuli being separated from bolts holding either one of the said two successive `insulating annuli and any third adjacent insulating annulus so that the bolts dn the two sides of any .one insulating annulus are separated and insulated from each other. 5. In a circuit breaker the combination of` a iixed contact, a movable contact and a pressure chamber comprising with suitable end pieces ak stack of at least 5 annuli, successive annuli being alternately of conducting and of insulating materials, and longitudinal bolts for holdnig said annuli together to provide a gas-tight chamber insulated between the ends, said conducting annuli each having external diameter less than the external diameter of said insulating annuli, and said bolts being spaced radially away from said conducting annuli and spaced around inside the circumference of said insulating annuli so `that the bolts holding the rst two insulating annuli together are spaced apart from the bolts holding the second and third insulating annuli, thereby holding said conducting annuli tightly between adjacent insulating annuli, and maintaining insulation between the bolts on one side of any one insulating annulus and the bolts on the other side of that annulus.

6. In a circuit breaker the combination of a gas-tight cylindrical chamber insulated between its ends, a contact in one end of said chamber, a contact-making rod entering the other end of said chamber through a gas-tight opening and attached outside said chamber to a piston operating in a gas-activated cylinder, and means for admitting gas under pressure to said chamber, openings in and through said rod placed to permit a ilow of gas from inside said chamber through said rod to said gas-activated cylinder, whereby the admission of gas under pressure to said chamber causes said piston to draw said contactmaking rod away from said contact, thereby opening the connection between said contact and said contact-making rod.

7. In a circuit breaker the combination of a gas-tight chamber composed of alternate conducting and insulating annuli, said conducting annuli having outside radius less than that of the insulating annuli, bolts in the outer rims of said insulating annuli holding said conducting annuli in compression between adjacent insulating annuli, each bol-t being spaced and insulated from adjacent bolts so the bolts on one side of any one insulating annulus are insulated from the bolts on the opposite vside of the annulus, gas-tight end pieces in said chamber, a centered contact in one end of said chamber, a longitudinally movable contact-making rod entering the other end of said chamber, means for moving said rod toward or away from connection with said contact and means for introducing gas under pressure into, said chamber.

8. In a circuit Abreaker as set forth in claim 'l the elements claimed therein, in combination with an insulating tube in which said gas-v-tight chamber is enclosed for the maintenance of external insulation thereon.

9. In a high-voltage circuit breaker the `combination of a cylindrical chamber, concentric separable contacts therein, means for opening and closing Asaid contacts, .and means for maintaining gas at high pressure in said chamber, said chamber being lmade of concentric alternate 9 conducting and insulating annuli held tightly together by attachments to said insulating annuli, said attachments being distributed `and spaced to hold all conducting annuli tightly in compression, and to have attachments holding successive conducting annuli insulated from each other.

LINDSAY M. APPLEGATE.

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

UNITED STATES PATENTS Number Number Name Date Dempster May 28, 1907 Thomson Apr. 26, 1921. Graves, Jr. Dec. 29, 1936 Rawlins June 1, 1937 Lindstrom May 6, 1941 Strom et al Apr. 18, 1950 FOREIGN PATENTS Country Date Germany Apr. 8, 1914

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