US1319907A - Means for extinguishing arcs. - Google Patents

Description

E. 0. SCHWEITZER ANDv N. J. CONRAD.

MEANS FOR EXTINGUISHING ARCS.

APPLICATION FILED SEPT. l0. l9l6.

Patented oct. 2B, 1919.

E. 0. SCHWEITZEB ANI) N. J. CDNRAD.

MEANS Foa exmuxsnmc Aucs.

' APPLICATION FILED SEPT. IB. 19'16. I v 1 ,3 1 9,907. mem-.ed oct. 28, 1919. r

' 2 SHEETS-SHEET 2.

as' IIJ j UNITED strainsY PATENT orrroE.

EDMUN D O. SCHWEITZER AND NICHOLAS J'. CONRAD, l01|? CHICAGO, ILLINOIS, ASSIGNORS TO SCHWEITZEB & CONRADL OF CHICAGO, ILLINOIS, A CORPORA.I.I( 1 I' 0g` ILLINOIS MEANS FOR EXTINGUISHING ARCS.

Specification of Letters Patent Patented Oct. 22S, 1919.

Application led September 18, 1918. `Serial No. 120,625.

Y l all u'hom Ait may concern: Be 1t known that we, EDMUXD Scnwrrzna and NICHOLAS J. CONRAD, cititype of apparatus specifically described in those patents and for use in connection with switching or current interruptingdevices zens ofthe United States, residing at Chigenerally. 55 5 cago. in the count-y of Cook and State 0f The primary aim `of this invention is to Illinois. have invented a certain new and provide improved arc extinguishing liquid useful Improvement in Means for Extinmeans for use in current interrupting appaguishing Arcs. of which the following, is a ratus. The invention aims further to profull. clearconcise, and exact description, vide an improved container ofinsulation 60 l reference being had to the accompanying for use in fusible cut-outs of the type above drawings, forming a part of this specifiset out. Other and further objects will slpcation f .pear from the following description.

Our invention relates to means for ex- Heretofore in liquid inclosed fuses and tin uishing arcs. switches oil has been very widely used. Oil 65 Vl n the matter of interrupting heavy curhas a number of marked disadvantages,

rents of electricity either for normal switchamong which are its inflammability and liking or in the case ofV protective apparatus lihood of causing an explosion and its hygrothe physical separation of the electrical scopic character. This latter quality causes contacts or conducting parts where the cur-A it to deteriorate in insulating strength and 70 rent is to be interrupted is a relatively sim- .require renewing. When it leaks out of a. ple matter in itself. However. the sepaswitch chamber, it discolors and soils the ration of the ph sical conducting pieces floor leaving unsightly grease spots. does not necessari y entail an interruption As an improvement upon oil for current of the current flow as thecurrent iow coni interrupting apparatus -we have heretofore 75 tinues in the shape of an arc of greater einplo 'ed carbon tetrachlorid. This is a.

or less severity. depending upon numerous thin reeowing liquid 'having a low boilfactors such. as voltage, frequency, speed ing point (76.5 C.) very volatile, having a of separation of the conductors, resistance high vapor pressure and fairly low freezing and reactance of the circuit, and the like. point: 'We have found that it has decided 30 rhether the condition of interrupting advantages over oil as it has a high insulatthecurrent flow be caused inl a purely ing value, high break dow'n strength, does switching operation or whether in the rupe not absorb water unduly and is a fairly stature of a fusible cutout` or in some otherV ble material. But useful aswe have found automatic overload circuit-breaking device it, it has defects which render it difficult 85 35. the v'same consequence of .breaking the conto employ with complete satisfactionV in aptinuit of t-henormal conducting path re- "paratus of this type. Perhaps the reatest sults inthe formation vof an arc of greater disadvantage of carbon tetrachlori isthe or less severity. `The'increase in voltage fact'that it attacks nearly all` metals. This which has occurred in the recent decades action on metal is increased by the .presence 9C 40 has greatly increased the difficulties of ,inf of moisture or light. Another great difterrupting current How. v culty isits tendency to evaporate when l lVe have heretofore developed a number left in an o en vessel. `Its vapor pressure of fusible cut-outs tomeet special condition is` high an boiling point relatively low. of breaking current flow asjshown in pat- Asa consequence we have found it unsuited 95 ents granted to us-Nos.' 1008496.,`1033384, for use in the usual open well, such as is 1050493 and 1135548, and while those patemployed commonly in oil switches. Due ents refer particularly to fusible cutlouts vto its great `fluidity it escapes very quicklytheir teaching' applies as well to other ,through even a minute` openin and as it switching operation.. Our present invenleaves no' telltale stain, it is di cult to as- 10D tion providesy certain specific improvements .certain the conditionof theswitch.

particularly for use in connection with the Wev have discovered a class 0f substances which are better adapted for use as arc extinguishing liquids than any heretofore known.

These substances have characteristics more favorable for use in this connection than carbon tetrachlorid or oil. These substances are poly-chloro-derivatives o f ethane and ethylene.

The particular substances which we have` discovered to be valuable in this connection are Tetrachloro ethylene (C (31,)

Tetrachloroethane Ca ,CIJ

Pentachloroethane (3J-1G15) Hexach-.loro'ethane (C,C1) These substancesA may be employed as mixtures or solutions' in any desired proportion. The first three substances are liquids at room temperature and may be employed alone. The last substance is solid at room temperature`and ma be dissolved in the other liquids. The esired density may be obtained by suitable mixtures or solutions of the substances.

In order to make clear to those skilled in the art one particular manner of carrying out our invention we shall now point out in connection with the accompanying drawings one s ecifio manner in which the invention maiy e embodied. v

n the accompanying drawings we have illustrated .a form `of fusain which the above mentioned liquids are. employed to good advantage.

Figure 1 is a longitudinal section of a fuse embodying our invention;

Fig. 2 is a. similar v iew of the same after the fuse has blown;

Fig. 3 is a fragmentary sectional view of a fuse of modified form; and

Fig. 4 is a cross section of a switch embod 1n the invention.

e ses above illustrated are of the type shown'in our above mentioned' atente. body of the fuse is formed o a sleeve or tube 1 of insulating material. Upon the ends of the sleeve or tube 1 are secured the metal ferrules 2 and 3 which form terminals for the conducting parts o'f the fuse contained within the sleeve 1.

The lower ferrule 3 isclosed olf b a suit- `able head, bearing a mounting stu 4. In

the form shown in Fig. 3 theu per ferrule is provided with an annular p ate or ring 5 which is soldered or otherwise interconnected to the interior surface thereof above` the end of the insulating sleeve 1.

The annular rin 5'is connected by fusible wires 6 to a meta stud 7 which in turn is connected to the lower ferrule`3.by the ilexible stranded conductor 8. A coll s ring 9 which is normally under tension is astened at its lower end to the head of the ferrule 3 and at its upper end to the stud 7. A liquid directing or spraying member 10 is mounted y director 10 is in fact a plunger iittin more or less closely into the tube1 and havin an aperture through the center thereo'f a ut the metallic stud 7. A wire 11 passes through the plunger 10- and the stud 7 thereby sultabl connecting these two arts.

In the orm shown in Fig. 3, tlie plunger 10 fits quite loosely within the insulating tube or sleeve l, the stud 7 and plunger 10 being guided by suitable lingers 12 formed of wire and secured to the stud 7 In this form of the device the stud 7 projects up through a non-conducting Washer 13 and is held 1n place by a wire 14 which passes through the stud 7 and is secured at each end under suitable screws fastened to the ring 5. The top of the stud 7 is provided with a removable screw 15 to which a number of fuse wires 6 are fastened.

In the form shown in Fig. 1 the fuse Wire l 6 fits closely in a hole or passage formed in the `non-conducting lug 16, which is preferably made o'f cork. he Wire 6 is normallyunder the tension of the spring 9 and is fastened at its upper end to a plug 17 which is secured to the cover piece or disk 18. The fuse wire 6 being of rather soft metal is not adapted to stand the strain imposed by the tension of the spring 9. We therefore employ a wire 21 of stronger metal to withstand the strain. This wire 21 is connected tothe stud 7 and to the plu 17. The fusible wire 6 is thus contained w olly within the cork plug 16 as the stud 7 and the plug 17 abut against said plug. The upper errule 2 is normally closed off by the cap 18, as is shown in both forms of fuse. This cap is carefnlly soldered to the top of the ferrule to prevent the evaporation or esca ve of the contents of the sleeve 1. The attac ioli' when the pressure becomes too great.

The sleeve or tube 1 is .normally substanp tially filled with an are extinguishing liquid which is introduced preferably through an opening in the head of the ferrule 3.

The operation of the fuse is la parent from the above description. In t e Ytype shown in Figs. 1 and 2 the non-conductin plu 16 serves to localize the heat 1n vtie fusible wire 6 and when thls wire is melted or fused, the tension wire 21 is 'subjected to a heav current. It is fused at once and the sprlng 9 draws the plunger 10 downward projecting a stream of arc extinguishing liquid 20 u on the .space where the are tends to form. 'like operation of the form shown in Fig. 3 is substantiall indentical so far as the extinguishment o the arc is concerned.

Vire have employed as the material of the sleeve or tube 1 vheretofore a piece of glass generatec y tubing. We have found that glass is Vsubject; to grave defects, chief of which is its lack of strength and uncertaint This is due largely to the fact that it is brittle and fragilel and is easily shattered. In case the arc extinguishing liquid 20 becomes lowered as by leakage or the like, the glass is subject to breakage from the.heat o'f the are or the sudden pressure of the explosion. It is also sensitii'e to tem erature changes particularly due to its dlerent' rate of thermal exansion as compared with metals with which 1t is employed, and it is therefore hard to make tight joints.

Another ditliculty has been the impossibility of machining the same.

To overcome these defects, we have made a number o experiments extending over a considerable time to find a substance which is suited to this purpose. The arc extinguishing liquid" which we have employed heretofore is carbon tetrachlorind, and, as this is an excellent solvent of nearly all gums, resins, fats, oils and the like, the 'problem of providing a suitable container which will not be attacked on the one hand by this carbon tetrachlorid or other liquid or be ermeable lto the passa e of the liquid theret rough, on the other hand, has been attended with great'diiculty.

Ye have discovered, however that a fiber sleeve impregnated with bakelite is suited admirably to this purpose. The sleeve is practically unbreakable; it is not attacked by the are extinguishing liquid whether it be oil, carbon tetrachlorid or the poly-chloro derivatives which we have above set out. This substance can be formed in dies to any desired form; it can be machined and in fact vserves admirably for the purpose.

We have found further that it is insoluble in carbon tetrachlorid not only to the extent that it does not spoil. the insulating properties of the liquid but also to the extent that `the strength and insulating qualities of the sleeve are not im aired.

stances also have high The arc extinguis iing liquids which we have discovered and enumerated above are all characterized by the fact that they are good dielectrics,I that they are non-infiammable and have "aluable fire extinguishing or arc extinguishing prorties. These subiling points and low vapor pressures as compared to carbon tetrachlorid and therefore do not cause trouble due to evaporation as does carbon tetrachlorid. They are further characterized by very low freezing points as com-` paredto oil and except in case of-tetrachloro ethylene they have very low freezing points as compared' to, carbon tetrachlorid. The vapors of these substances 'do not form explosive mixtures with air as in the case of oil, and they do not stain or deface substances with which they come in contactas does oil. They are, however, very free running fiuids so that they are admirably adapted to the quick operation of projecting them upon th'e space where the arc is formed.

These substances are derived from the correspondingl carbohydrates by the substitution of one or more atoms of chlorin for correspondincI atoms of hydrogen. This may be accomplished in a variety of ways and for this purpose several different schemes of derivation are possible.

lVe are presenting below a table of propert-ies of these materials to point out to those skilled in the art the particular qualities of It can be seen that tetrachloroethylene is aV perchloro derivative 4of an unsaturated hydrocarbon, namely, ethylene, C2H4, while the other substances are poly-chloro derivatives of a saturated hydrocarbon, namely ethane C21-I5.

lVe do not intend to be limited to employ these substances in afuse structure only as they are equallv applicable for use in the well of a switch emplo ved for the usual switching opel-ation. owever, for this purpose the well about the switching element is closed to preventthe escape of the liquid b vaporizat-ion. A safety valve is provide for relieving the pressure within the closed well in case of excessive vaporizationas would be caused by a particularly heavy arc,.and an indicator is provided for indicating the level of the arc extinguishing liquid in the `well.

In Fig. 4 we have illustrated a form ofl switch embodying our invention. This switch comprises a closed vessel 20 provided with the safety valve 22 and liquid level indicator 23. The closed casing 20 includes a cover 21 through which project electrical conductors terminating in the stationary switch contact members 24. These contact members are of the 4form well known in the art and need not be specifically described here. The conductors 25 which are connected to said Contact members are led through the cover 21 by means of suitable insulators 26 which may be of any preferred type. These insulators are sealed into the cover 21 so that a tight joint is maintained.

A movable switch member 27 adapted for reciprocation into and out of contact with the stationary 'contact members 24; is mounted on a suitably insulated rod 28 which is guided in the cover 21 and connected by suitable link mechanism through anoperatmore of the halogenated hydrocarbons as heretofore set out. We have found that they4 are far superior to oils because of the freedom from carbonization. We find that they are not as volatile as carbon tetrachlo- -rid and will not leak through minute crevices as will carbon tetrachlorid. The operation of the structure above described is obvious. We have found that the' ilnproved operation of switching mechanism constructed in accordance with our invention is due, not to the .arrangement ofthe switching mechanism in the particular form shown in Fig. 4, but to the improved operation of the arc extinguishin liquid which forms the subject mattero our invention. We have found that it is not necessary to move the movable contact members downward in the liquid as is necessary under the present ractice where oil is employed, as the liqui semployed by us are not subject to carbonization and consequently no deposit is formed which would tend to cause a flash-over or a weakening of the insulat-y ing strength of the liquid.

We claim;

1. In combination, a closed container, comprisin a sleeve of porous insulating material impregnated with a condensation product of a phenol and formaldehyde, said container having metallic current conductcomprising a sleeve of ber implregnated with a condensation product of a p enol and formaldehyde, said container having metallic current conducting terminals'forming a part ,of the inclosure, a fusible element connected between said terminals Vand an arc extinguishing liquid, said liquid comprising a polychloro derivative of a hydrocarbon.

3. In a device of the class described, a closed container, a pair of circuit terminals in said container adapted to be se arated for breaking the flow of current an an arc extinguishing liquid Vcompletely covering said terminals for extinguishing the arc between said terminals, Vsaid liquid comprising a polychloro-derivative of a hydro-carbon and means for relieving the pressure in said container-` 4. In combination, a,closed container, a body of liquid in the container, said liquid comprisin a polychloro-derivative of ,a hydro-car on, said container being made of opaque material, and having a air of metallic terminals exposed on the interior thereof to said liquid, said terminals having means for interrupting a flow of current within said body of liquid. y

5. In combination, a closed, substantially fluid-tight container adapted to retain a predetermined pressure, a body of arc extine guishing liquid held in said container, said liquid comprising a polychloro-derivative of ahydro-carbon, a ypair of metallic terminals submerged at all times in said liquid, said terminals `being adapted to draw' an arc therebetween under the surface of the liquid to interrupt a How of current.

In witness whereof, we hereunto subscribe our names this 16th day ofv September A. D.

' EDMU ND O. SCHWEITZER.

"- NICHOLAS J. CONRAD.

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