USRE14897E - Means for extinguishing arcs - Google Patents

Description

E. 0. SCHWEITZE'R AND N; J. CONRAD.

MEANS FOR EXTINGUISHING ARCS.

APPLICATION FILED APR I6, 1920.

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E. 0. SCH'WEI TZER AND N. J. CONRAD. MEANS FOR EXTINGUISHING ARCS. v I APPLICATION FILED APR I6, I920. Reislsu ed J um 22, 1920,

W M W W UNITED, STATES PATE T OFFICE.

EDMUND, O. SOHWIIITZER, OF CHICAGO, AND NICHOLAS .T. CONRAD, OIli WILIDIET'IB,

ILLINOIS,'ASSIGNORS TO SCHWEITZER & CONRAD, OF CHICAGO, ILLINOIS, A (JOB- PORATION OF ILLINOIS.

MEANS FOR EXTINGUISHING ARCS.

DriginaI No. 1,319,907, dated October 28, 1919, Serial No. 120,625, filed September 18, 1918. Application g for reissue filed April 16, 1920. Seria1 No. 374,489.

To all whom it may concern:

Be it known that we, EDMUND O.

ScHwErrzEn and NICHOLAS J. CONRAD, citi-' zens of the United States, residing at Chicago and lVilmette, respectively, in thecounty of Cook and State of Illinois, have invented a certain new and useful Improvement in Means vfor Extinguishing Arcs, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

' tacts or conducting parts where the cur Our invention relates to means for extin uishing arcs. n the matter of interrupting heavy currents of electricity either for normal switching or in the case of protective apparatus the physical separation of the electrical conrent is to be interrupted is a relatively ,simple matter in itself. However, the separation of. the physical conducting pieces does not necessarily entail an interruption of the current flow as the current flow continues in the shape of an arc of greater or less severity depending upon numerous factors such as voltage, frequency, speed of separation of the conductors, resistance and reactance of the circuit, and the like.

Whether the condition of interrupting the current flow be. caused in a purely switching operation or whether in the rupture of a fusible cut-out, or in some other automatic overload circuit-breaking device the same consequence of breaking the continuity of the normal conducting path results in the formation of aware of greater or less severity. The increase in voltage which has occurred in the recentdecades has greatly increased the difficulties of interrupting current flow.

lVe have heretofore developed a number of fusible cut-outs to meet special condition ofbreaking current flow as shown-in patents granted to usNos. 1008496, 1033384, 1050493 and 1135548, and while those patents refer particularly to fusible cut-outs their teaching applies as well to other switching operation. Our present invention provides certain specific improvements particularly for use in connection with the type of apparatus specifically described in those patents and for use in connection with scopic character.

vide an improved container of insulation for use in fusible cut-outs of the type above set out. Other and further objects will appear from the following description.

Heretofore in liquid inclosed fuses and switches oil has been very widely used. Oil has a number of marked disadvantages, among which are its infiammability and likelihood of causing an explosion and its hygro- This latter quality causes it to deteriorate in insulating strength and require renewing. Vhen it leaks out of a switch chamber, it discolors and soils the floor leaving unsightly grease. spots. As an improvement upon oil for current interrupting apparatus we have heretofore employed carbon tetrachlorid. This is a thin 'freeflowing liquid having a low boiling point (76.5 ,C.) very volatile, having a high vapor pressure and fairly low freezin point. We have found that it has decide advantages over oil as it has a high insulating value, high break down strength, does not absorb water unduly and is a fairly stable material. it, it has defects which render it difficult to employ with complete satisfaction in apparatus of this type. Perhaps the greatest disadvantage of carbon tetrachlorid is the fact that it attacks nearly all metals. This action on metal is increased by the presence of moisture or light. ficulty is its tendency to evaporate when left in an open vessel. is high and boiling point relatively low. As a consequence we have found it unsuited for use in the usual open well, such as is employed commonly in oil switches. Due to its great fluidityit escapes very quickly through even a minute opening and as it But useful as we have found Specification of Reissued Letters Patent. Rei d Ju 22 1920 Another great dif- Its vapor pressure 'These substances have characteristics more.

favorable for use in this connection than car- "bon tetrachlorid or oiLThese substances are poly-chloro derivatives of ethane and eth lene. 'ij

.he particular substances which we have discovered-to be valuablein this connection are Tetrachloro ethylene ('C CL) Tetrachloroethane (C H' Cl Pentachloroethane (C HCl5) Hexachloroethane (C Cl These substances, which may be designated broadly as poly-halogen-derivatives, more particularly poly-chloro-derivatives of hydrocarbons having more than one carbon atom in the molecule, may be employed as mixtures or solutions in any desired proportion. The first three substances are liquids at room temperature and maybe employed alone. The last substance is solid at room temperature and may be-dissolved in the other liquids. The desired 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 specific manner in which the invention ma be embodied.

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

Figure lii s a longitudinal section of a fuse embodying our invention;

Fig. 2 is a similar View of the same after the .fuse has'blown;

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

F ig. 4 is a cross section of a switch embodyin the'invention.

. The usesabove illustrated are of the t pe shown in our above mentioned patents. he body of the' fuse is formed of a sleeve or tube 1 of insulating material. -Upon the ends of the sleeveor tube 1' are secured the metal ferrules 2 and 3 which form terminals for the conducting parts of the fuse contained within the sleeve 1.

The lower ferrule 3 is closed off by asuitable head, bearing a mounting stud 4. In the form'shown' in Fig. 3' the upper ferrule is provided with an annular plate or ring 5 which is soldered or otherwise intercom nected to the interior surface thereof above ble stranded conductor 8. A coilspring 9 which is normally under tension is fastened 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 In the orm shown in Fig. 3, the plunger,

10' fits quite loosely within the insulating tube or sleeve 1, the stud 7' and plunger 10' being guided by suitable fingersf12 formed of wire and secured to the .stud7.-

In thisform of the device the stud 7' projects up through a non-conductingwasher 13 and is held in place by a wire 14 which passes through the stud 7 and is securedat 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 6 fits closely in a hole or passage formed in the non-conducting Eng 16, which is preferably made of cork. he wire 6 is normally under the tension of the spring 9 andis fastened at its upper end to a plug 17 which issecured to the cover 'iece or disk 18; The fuse wire 6 being 0 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.

The fusible wire 6 is thus contained wholly This wire 21 is eonnected to the stud 7 and to-the plug 17 within the cork plug 16 as the stud 7 and the plug '17 abut against said plug. The upper ferrule 2'is normally closed off by the cap 1 18, as is shown in both forms of fuse. This cap is carefully soldered to the top of the ferrule to prevent the evaporation or esca e of the contents of the sleeve 1. The attac mentiof this cap is such that it will be blownoff when the pressure becomes too great.

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

The operation of the fuse is apparent from the above description. In the type shown in Figs. 1 and 2 the non-conductingplu 16 serves to localize the heat generated in t e fusible wire 6 and when this wire is "melted or fused, the tension wire 21 is sub.-

jected to a heavy current. It is fused .at once and the spring 9 draws the plunger 10 downward projecting a stream of are extinguishing liquid 20 upon the space where the arc tends toform. The operation of the form shown in Fig.substantially identical so fares thez-extinguishment of the are 1s concern We have. employed as the material of the sleeve or tube 1 heretofore a piece of glass admirably to this purpose.

tubing. Ve have found that glass is subject to grave defects, chief of which is its lack of strength and uncertainty. This is due largely to the fact that it is brittle and fragile and is easily shattered. In case the arc extinguishing liquid becomes lowered as by leakage or the like, the glass is subject to breakage from the heat of the are or the sudden pressure of the explosion. It is also sensitive to temperature changes particularly due to its different rate of thermal expansion as comparedwith metals with which it is employed, and it is therefore hard to make tight joints.

.Another. difficulty has been the impossibility of machining the same. v

To overcome these defects, we have made anumber of experiments extending over a considerable time to find a substance which is suited to this purpose. The are extinguishing liquid which we have employed heretofore is-carbon tetrachlorid, and,v 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 permeable to the passage of the liquid therethrough, onthe other hand, has been attended'with great difficulty. I

\Ve have discovered, however, that a fiber sleeve impregnated with. bakelite 1 is suited The sleeve is practically unbreakable; it is not attacked by the are extinguishing liquid whether it be oil, carbon tetrachlorid or the other pdlychloro 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 serves admirably for the purpose.

Ye have found further that is insoluble in carbon tetrachlorid. not onlyto 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 impaired.

The above described class of compounds,

which wehave discovered to be especiallyadapted for use as arc-extinguishingliquids in devices of the character above set forth, are all characterized by the fact that they are good dielectrics, that .they are non-inflammable and have valuable fire extinguishing or are extinguishing properties. These substances also have high boiling 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 compared to oil and except in case of tetrachloroethylene they have verylow 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 contact as does oil. They are, however, very freerunning fluids so that they are admirably adapted to the quick operation of projecting them upon the space where the arc is formed.

These substances, which may be regarded as chlorin substitution or addition products of the correspondin hydrocarbons, may be prepared commercially according to various methods well known in the chemical art.

Ve are presenting below a table of properties of these materials to point out to-those skilled in the art the particular qualities of It can be seen that tetrachloroethylene is a pe rchloro derivative of an unsaturated hydrocarbon, namely, ethylene, C H while the other substances are poly-chloro derivatives of a saturated hydrocarbon, namely ethane C H these substances ina fuse structure only as they are equally applicable for use in the well of a switch employed for the. usual switching operation. However. for this purpose the well about the switching element is closed to .prevent the escape of the liquid by vaporization. A safety valve is provided for relieving the pressure within the closed Well in case of excessive vaporization as would be caused by a particularly heavy arc, and an indicator is provided for indicating the level of the are extinguishing li uid in the well.

n Fig. 4 we have illustrated a form of switch embodying our invention. This switch comprises a closed vessel 20 provided with the safet valve 22 and liquid level indicator 23. he closed casing 20 includes a cover 21 through which project electrical conductors terminating in the stationary switch contact members These contact members are of the form well known in the art and need not be specifically described here. The conductors 25 which are 'con:

insulators 26 which may be of any preferred type. These'insulators are sealed into the cover 21 so that a tight joint is maintained 100 We do not intend to be limited to employ 12s nected to said contact members are led v through the cover 21 by means of suitable- A movable switch member 27 adapted for reciprocation into and out of contact with Y 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 an operating spring 29 and suitable setting means such as the rod 30 for closing the switch. A

controlling magnet 31 which is placed in series relation with the line controls a pawl or catch 32 which is adapted to engage in a suitable notch 33 in the rod 28. A spring 34 normally tends to cast the nose of the I pawl into the notch.

The closed container 20 holds a body of liquid 35. This liquid ma be any one or more of the halogenated iydrocarbons as heretofore set out. We find that they are not as volatile as carbon tetrachorid and will not leak through minute crevices as will carbon tetrachlorid. The operation of the structure above described is obvious.

' \Ve have found. that the improved operation of switching mechanism constructed in accordance with out invention is due, not tothe arrangement of the switching mechanism in the particular form shown in Fig. 4, but to the improved operation of the arc extinguishing liquid which forms the subject matter of pur invention.

lVe claim:

1. In combination, a closed container, comprising a sleeve of porous insulating material impregnated with a condensation product of a phenol and formaldehyde, said container having metallic current conducting terminals forming a part of the container, a fusible element connected between said terminals and an arc extinguishing liquid inclosed by said container.

2. In combination, a closed container,

I comprising a sleeve of fiber im regnated carbon having-,more than one carbon atom in the molecule, and means for relieving thepressure in said container.

. 4. In' combinatlon, a substantially closed container, a body of liquid in; the container,

said liquid comprising a' polychloro-derivative of a hydrocarbon, said container being made of opaque material, and havinga pair substantially fluid-tight container adapted to retain a predetermined pressure, a body of arc extinguishing liquid held in said container, said liquid comprising a polychloroderivative of a hydrocarbon having more than one carbon atom in the molecule, a pair 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 flow of current.

6. In a device of the class described, a substantially closed container, a pair of circuit terminals in said container adapted to be separated for breaking the flow of current, and an arc extinguishing liquid disposed within said container in arc extinguishing relation to said terminals. said liquid comprising a polychloro-derivative of a hydrocarbon having more than one carbon atom in the molecule. v

7 In a device of the class described, a substantially closed container, a pair of circuit terminals in said container adapted to I be separated for breaking the flow of current, and an arc extinguishing'substance in fluid condition disposed within said container in arc extinguishing relation to said terminals, said material comprising a polyhalogen derivative of a hydrocarbon having more than one carbon atom in the molecule.

8. In a device of the character described, the combination, with a suitable container, of circuit forming elements insaid container separable to open a circuit, and an are extinguishing liquid disposed in relation to said elements operative to extinguish an arc resulting from separation thereof, said liquid comprising a non-inflammable and relatively non-corroslve halogen derivative of a hydrocarbon, said derivative having a high boiling point, low vapor pressure, and

good dielectric properties.

' 9. In a device of the character described, the combination, with a suitable container, of circuit forming elements in said container separable to open a circuit, and an are extinguishing liquid disposed in relation to said elements operative to extinguish an arc resulting from separation thereof, said liquid comprising a non-inflammable and relatively non-corrosive chlorin derivative of a hydrocarbon having a boiling point of ap roximately at-least 119 C. v

n witness whereof we hereunto aflix our signatures.

EDMUND O. SCHWEITZER. NICHOLAS J. CONRAD,

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