US1983150A - Electric circuit breaker - Google Patents

Description

Dec. 4, 1934. R5|GMAN 1,983,150

ELECTRIC CIRCUIT BREAKER Filed Mayrle, 1951 6. Maw

assenso I' BBEAKEB ICaIii., assigner of one-V' l half to Nelis A. Sim neem, Alameda, Calif;

u. appuccacnmiy ifs, 1931, serieu No. saisinel c claims. 1 (casos-.issy

I The invention relates -to electric circuit breakers capable of being used'for interrupting cur- 'rentsrw V'Il'he breaking of an electric circuit carrying a large current load is'one of the most serious problems that confronts a power distributing system.

' The breaking of such a'circuit is generally accompanied by arcing, burning of contact points and ,other characteristics which are ruinous to the 1o circuit breaking apparatus and invariablyA introduce' undesirable-electrical eifects inthe power lines. .f -nh An ideal circuit breaker would be .one that would on' interrupting the iiow of current, place a high insulating medium'` into the circuit, and

quench any arc that may be formed, in a'. minimum length of time. To meet these requirements,

manufacturers have concentrated their eiforts on the development of a breaker` which is characterv ized'by the, sep`arationjof solid conductors ina fluid insulating medium.'y lPerhaps the most successful breher `of this type is the commonlyfused4 '.oil breaker wherein copper contact points areseparated/while completely'submergedin oil. Oil .25 is usedas aninsulating medium between the con: tacts andserves toiocclude the air', which action reducesthe ofthe copper or other electrodes to a Thistype of breaker has severalderects. nue. to the comparatively mw` .30 .dielectric strength of oil, the contact. points are necessarily drawnapart for a considerable dis.

. tance when a'higliv voltage line is tobe broken. This feature tates the useof alarge sized tank for housing the apparatus. Further the oil having the best insulating properties also has a high' viscosity whichvproduces a strong resisting force to the movement of -any body through the oil'and thus it-is almost impossibleto widely sepa- 'rate the contact pointswith any great velocity. It

i 4o' is considered good operation tocompletely open a circuit under load with sucha breaker in'approxi.-

v mately five to eight sixtiethsoi a second vwhich` wculdconstitute a five to eight cycle period on a line operating from a source using a frequency of 4,5 sixty cycles a second. vFurther .due to. the vaporizing and burning of the oil intermediate the arc,

a 'very high pressurev is created. and accordingly aheavlly vbuilt tank casing is required to prevent.

bursting of the breaker. .It has also been found thats breaker isjoften rendered inoperable due to the fusing of the copper contacts whichV maybreaker.

To obviate these many defects, I, have conresult from an excess load passing through the l L caved .and deveicpeu the nec' of reversing che .the oilv 'may be employed as an insulation m'edium. This gain in the dielectric strength of the linsulating medium between the electrodes obviously'will reduce the necessary distance that the electrodes must separate in my breaker to about one third the separating distance required in the oil type cfbreaker. u i

Secondly, in 'my devicethere isv only a small f shearing force ofthe liquid column and a slight -bearing friction force acting to resist the separation ofthe contact points,'and thus the Icircuit may be completely opened in an extremely'short interval of time.

Thirdly I may .use a liquid conductor such as lmercury which onbengseveredwhile under a 30 .load will produce an arc causing the formation of a vaporv possessing 'the 'characteristic of being' strictly unidirectional in its conduction of an electric current. This last feature isvery benencial in the breaking of an alternating current cira5 cuit for should the'arc last eight sixtieths of a' second on va sixty cycle system, only four complete cycles or eight half cycles wouldbe conducted durng the duration of the arc.. This unidirectional Vfeature also helps materially in the quenching of the arc, since should the arc form on a positive half cycle, it will disappear on the followingV negative half cycle, and thus ona 60 cycle system there would be a period of ,1/120 of a second in which to place enough* insulating 95 material between 'the contact points to prevent the arc from being reestablished on the following positive half cycle. Further a liquid. conductor such-as mercury has none of the defects as cited against the solid contacts, as there is no possibility of my apparatus ever becoming inoperable due to burned 'or fused contacts. It should also be clear that the liquid conductor could easily and quicldy be drained from the apparatus and freshliquid substituted therefor without incurring 105 any great loss of time and without disassembling Y -the breaker. f

will be set forthl in the .following description of no lli) the preferred form of the invention which is illustrated in the drawing accompanying and forming part of the specincation. It is to be understood,

Figure 3 is a side elevatign of a difl'feurentform ofmy invention. y ,A

Figure 4 is a' plan view of a switch illustrating still'another form of my "invention Figure 5 is an end sectional view taken on the line 5-5 of Figure 4. Y

Figure 6 is a fragmentary plan view-.of a modifled form of the unit shown in Figure 4.

.The unit of my invention,- as illustrated in Figure4 1, comprises a fluid conductor 'I such as mercury .conned in an insulatingy .casing 8 which is of such structure as toprovide two-:duid reservoirs/9 intercormectedbysumma-.141.` The casing 8 also provides two .hollowtcylinders 12y and 13 v ofwhich cylinder,13 extends through the column 10-while cylinder.12 is positioned at. one side of the column andisconnectedthereto-by a small passage 14.-..;Mounted ,for -reciprocation inthe cylinder 131s .apiston valve'l arranged to sever the iuid column 10 and-madefofa material of piston carries a lateralbore 17 throughwhich the fluid may form :tn-unbrokenA connection between the reservoirs when the piston-isso. positioned as to dispose a portion -of the bore 17. in engagement with the column 10.- In'the cylinder'12 is slidably mounteda piston 1-8which has. connection with-:the fluid on -itsLl inside. -face and is arranged to vary the pressure onthe uid system upon movement of the-piston 16 to establish or sever communication'- between'the. reservoirs 9.

The desirability of; varying suchpressure is to assist in the most effective `making and breaking of connection ofthe fluid column.' Ati-.the instant of connection of portions Aoffthefiiuid column the presence of small quantities'rof gas or lvapor entrapped between the columns would impair connection and perhaps produce an arc causing the further formation of gas or vapor between the fluid portions. lTo-insure the proper' closing of the fluid portions, such :portions are preferably urged into closed position under the pressure produced by the piston'l. On .the other'hand at the ns'tantxof-break, an yarc:forms'producing a conductive mercury vapor. The conductivity of such vapor is vproportionalto: the.` vapor pressure. Accordingly to reduce'rthe'conductivity of such Vapor-and tothereby facilitate the breaking of the electric circuit,- the-pressi1re atthe instant of break is preferably relieved and comparably low.

to place the Vfluid'in communication :with cylinder 12 under pressure and movement of the piston 16 to sever the fiuid column releases the pressure on the piston 16 and accordingly on the uid.

Any suitable means may be provided for actuating the piston 16. As here shown, the mechanism compriseslalever 25 pivotedv intermediate its ends to the-casing` as at 27gand,hav`ingf9ne end in engagement with piston 16 and its other end fastened to a crank wheel 23 through the link 24.

As will be clear from Figure 1, rotation ofthe wheel 23 will produce oscillation of the lever 25 to cause a corresponding movement of the piston. A suitable electric circuit through the breaker 'is afforded through the medium of a set of suitable terminals 28 and two associated electrodes 29. The latter are embedded in the casing and extend into the fluid reservoirs 9. lLeads 30 serve to connect the terminals to the electrodes.

It will now be clear that on displacement of the piston 16 to place the bore in or out of communication with the columns, the column portions on each side of the piston will be either connected or separated to thereby make or break an electric current passing through the column between the electrodes.

In Figure 2 wherein a modified form of the unit of my invention is disclosed, the mode of operation is nearly the same as that described for the apparatus shown in Figure 1. In this embodiment a tapered valve plug 32 is rotatably mounted in a correspondingly tapered seat provided in the casing member 33. As in Figure 1, a fluid column 34 is arranged to be severed by the plug 32 which carriesa lateral bore 35. Two electrodes 37 are embedded in the casing and extend into the uid column on either side of the plug member. 0n rotating the plug, the bore 35 may be passed into or out of registration with the column to thereby makey or break a continuous path of conducting fluid between the electrodes. A cam 38 is carried by the plug and actuates a pair of pistons 39 for placing the fiuid under pressure during the instant of ,fluid connection between the electrodes.

I have illustrated still another modified form of my invention in Figure 3. This structure comprises a casing member 41 having a portion which provides a semicircular bearing surface 42 for 'a movable member 43 pivoted intermediate tothe casing as at 44 and having one extremity 46 seating in the bearing surface 42. The opposite end of the movable member forms a handle 47 for conveniently actuating the member. Formed in the casing and opening onto the bearing surface 42 are two bores 48. A trough 49 is formed in the end 46 of the movable member and is of such length as to be simultaneously in registration with the two bores 48. With the trough and bores filled with a conducting fluid and in registration with each other, a continuous column of fluid may form'between electrodes 50 provided in the bores,

Mii)

and thus an electric circuit is completed through the switch. It should further be clear that on moving the handle 47 the trough may be shifted from engagement with one of the bores and the electric circuit through the switch thereby opened.

In Figures 4, 5 and 6 an embodiment of my invention is shownwherein'three circuits may be simultaneously opened or closed. In this arrangement, an elongated tapered valve plug 51 is slidably carried in a seat 52 formed in the casing 53. At each side of the seat and connected thereto by passages 56, are reservoirs 5,4. On sliding the plug in the seat, lateral passages 55 reo provided in the plug, move into or out of registration with the passages 56, whereby a continuous or interrupted column of iiuid will be formed between the electrodes 57 which as here shown are submerged in the reservoirs 54. Preferably a flat spring 58 is fastened to the casing directly over the seat and slidably engages the plug member 51 to maintain the latter in seated position.

yIn order to provide a switch that will carry a heavyload an embodiment of my invention as submitted in Figure 6 may be used. In this form of the invention copper blocks 61 and 62 are shunted across the fluid path and are so positioned respectivelyl on the casing 63 and on the plug, member 64 as to arrive in operative engagement after the circuit has been closed through the iiuld, and to disengage before the circuit is opened by the breaking of the iluid column. I

To insure a smooth working yswitch, a very thin film of lubricant such as oil may be used for providing a substantially air tight seal between the sliding parts, and because of the extremely small cross section of such a iilm, its conductivity is negligible. 'I'he film will also serve in some cases to prevent the adhesion of the liquid conductor to theinsulator. Further, and of considerable importance is the functioning of the oil in filling the space between the movable breaker parts and in occluding from such space air as well as other gas or vapor generated by the breaking of the circuit, thereby replacing such air or vapor with a medium of considerably higher dielectric strength and consequently increasing the voltage breaking capacity of the breaker.4 In view of the foregoing it will be clear that the electric circuit breaker of my invention possesses all of the features hereinbefore referred to and is well adapted to accomplish the elimination of the defects inherent in the previous types of breakers as aforementioned.

I claim:

1. In a device of the character described, a casing` arranged to contain an electric conductving iiuid, a valve for separating said fluid into electrically disconnected portions and for allowing said portions to be electrically connected, electrodes for each of said portions, and means for increasing the pressure on said iiuid during the instant said valve opens to allow a continuous column of fluid to form between the said electrodes.

l2. In a device of the character described, a casing arranged to contain an electric conducting fluid, a valve separating said fluid into electrically disconnected portions in closed position, electrodes for each of said portions, and means for lowering the pressure on said fluid as the valve reaches closed position.

3. In a device of the character described, an

electric conducting fluid column, means operative to alternately interrupt and reestablish the continuity of said column, and means for effecting a change in pressure exerted upon the uid in said column upon operating said first named means.

.4. In a device of the character described, an electric conducting duid column, means for alternately interrupting and reestablishing the continuity of said column, and means operative solely uponfreestablishment of said continuity to exert an increase of pressure upon the fluid in the column.

5. In a device of the character described, an electric conducting` fluid column, means for al ternately interrupting and reestablishing the continuity of said column, and means for exerting an increase of pressure on the fluid inthe co1- umn to insure an effective reestablishment of the continuity of said coluxrm upon said first named means reestablishing said continuity.

6. In a device of the character described, an electric conducting iluid column, means for a1- ternately interrupting and reestablishing the continuity of said column, and means for lowering the pressure on the fluid in the column upon operation of said iirst named means' to interrupt said continuity.

` IRA R. SIGMAN.

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