US2065802A - Arc extinguishing device - Google Patents

Description

299 H. c. GRAVES. JR Z ARC EXTINGUIASHINGDEVICE Filed May'zo, 1953 2 shams-sheet 1 I N VEN TOR.

Y MQQQA Dec. 29, 1936. H. c. @QQ/AVES, JR 250359302 ARC EXTINGUISHING DEVICE Filed Mayzo. 1953 2 sngs-sneet 2 6av n Fmi m64. r1.5.

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5. 5 l l ATTORNEY.

Patented Dec. 29, 1936 UNITED STATES ARC EXTINGUISHING DEVICE Herbert C. Graves, Jr., East Bradford Townships Chester County, Pa., assigner to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of New Jersey Application May 20, 1933, serial No. 012,028

` s claims. (ol. 17a- 1318) My .invention relates to apparatus for extinguishing electricarcs and has for an object the provision of a simple, inexpensive, andI eilicient structure for quickly extinguishing an arc.

In accordance withone aspectl of my invention, the arc is drawn in a chamber formed by a` stack of laminations comprised preponderantly of laminations formed of material which when subjected to an arc liberates chilling gases, adjacent laminations being disposed to form upon the wall of the arcing chamber alternate ridges and pockets for introducing into the arc at a plurality of points the chilling gases to insure thereby `the rapid extinguishment of the arc.

In accordance with a further aspect of my invention the laminations are tightly pressed together to prevent radial ow of the gases, a small vent extending from one end of the charnber for axial flow of the gases through the chamber. To introduce gas turbulence and thereby augment cooling of the arc the laminations are arranged alternately to provide ridges and pockets along the inner wall of the arcing chamber.

My invention further resides in the features of combination, construction, and arrangement hereinafter described and claimed.

For an understanding of my invention and for A illustration of various forms thereof, reference is to be had to the accompanying drawings in which:

Fig. 1 is a sectional view of a circuit breaker.

Fig. 2 is a sectional view of a fuse.

Figs. 3 to 6 illustrate modifications of the washer construction.

Fig. '7 is a sectional view of a modification of Fig. 2 using external magnetic plates.

Fig. 8 is a modified fuse construction using solenoids.

Fig. 9 is an end sectional View taken on line 9--9 of Fig. 8.

Figs. 10 and 11 are end sectional and front views respectively of a modiiied fuse construction.

Figs. 12 to 15 illustrate modifications of the washer stacking arrangement'for fuses of the type shown in Fig. 11.

Fig. 16 is a sectional view of an insulator.

Fig. 17 is a sectional view of another type of insulator.

Fig. 18 is a fractional sectional elevation of the insulator unit of Fig. 17 provided with a plug having a lateral vent and laminations of the type shown in Fig. 10.

Referring to Fig. 1, when the movable cQntact 36 is moved downwardly, as by spring 31 upon release of latch 31a by the armature of trip coil 31h, an arc is drawn between contact 36and the fixed contact 38. 'Ihe arcing plates 39, 40 are connected respectively to the fixed and movable contacts, preferably in series with a coil 22h. VThe upper arcing plate `is disposed adjacent the region of engagement of the contacts and the lower plate is positioned adjacent the open position of the movable contact. Between the plates is disposed a stack of laminations 4i having holes which are aligned to form in effect a vertical chamber C in which the arc is drawn. The plates 4I are formed of suitable pressure withstanding insulating material, as fibre, etc., which liberate chilling gas, as hydrogen and/or carbon dioxide, when engaged by the arc. The bolt 43 which clamps the laminations 4| to and between the arcing plates is insulated from the plate, as by bushings and washers of insulation.

The arc is forced outwardly against plates 4| by coil22b for liberation of chilling gas. The laminations or plates 4I are spaced as by washers 44 to provide for abrupt changes in the crosssectional area of the arc path and to increase the turbulence of the arc gases and the generated gases and so enhance the chilling effect of the latter. The gases discharge through the spaces between the plates. 4

Preferably, the space between the upper arcing plate 39 and the top lamination of the stack is greater than the spacing between the lower lami-- nations to provide for greater volume of gas discharge at this region.` With this arrangement, the gas generated in the chamber has a radial movement outwardly through the narrow opening between adjacent laminations, and axial movement toward the upper arcing plate and thence outwardly through the wider opening between the top lamination and the arcing plate. The axial flow of gas is disturbed by the edges of the laminations introducing turbulence which forcesV the cooling gas into the arc stream and enhances its cooling effect.

The invention may also be utilized to advantage in circuit-interrupters of the fuse type. Referring to Fig. 2, the fuse wire 59 extends between the metal caps 60 and 6|, at least one of which is provided with an opening 62 of substantial area. Within the circular bore of the outer tube 63, which is of any suitable insulating material, is disposed a stack of washers 64 of an insulating material which liberates chilling gas upon contact with an arc. The holes in the washers are oi.'

such shape that they form a chamber C having converging wall structure, for example, such as shown in Figs. 3 to 6. The volume of the charnber is small so that high gas pressures and high gas velocities are produced affording high rupturing capacity for short length of chamber C. 'Ihe effectiveness of the fuse is-high for both large and small arcs due to the convergence of the wall structure, at generally the regions marked a.

To extinguish an arc quickly, it is desirable to have rapid generation of gas. This requires that the arc be in intimate contact with gas producing material. Other conditions being the same, the cross sectional area of an arc bears a direct relation to the current flowing. Assuming a fuse tube of circular cross section, a very small arc will have a small diameter and hence substantially only line contact will exist between the arc and the tube wall and gas will be generated along this line only. This forces the arc to the center of the tube away from'the chilling walls. As the diameter of the arc increases a larger and larger area of contact is established with a resulting increased rate of gas generation. This means greater pressure, greater velocities and a quicker extinguishment of the larger arc. A further increase in the arc dimension cannot increase the area of contact but will increase the intimacy oi' contact and hence the pressure. Thus the gas generation continues to increase with corresponding rise in pressure. A different diameter tube should be selected for each value of short circuit current. For a given diameter of tube, the arcquenching effectiveness falls ofi sharply for smaller,values of current, and for higher currenis excessively high pressures may be develope lBy employing converging walls toward the intersection of which the arc is forced in accordance with my invention, high quenching efliciency is obtained for a wide range of current values. The arc is forced to assume a substantially triangular -shape with two sides in contact with the walls. 'Ihe chamber may be constructed so that for maximum current iiow the pressure is not excessive, and it is nevertheless effective to `ciuench small arcs because of the aforesaid convergence of its walls.

The use of laminations or washers greatly simplies the construction of the chamber C having converging walls and/or changes in crosssectional area. One-piece tubing having the desired internal shape would either have insumcient resistance to internal pressure or would be too expensive.

The use of washers 64 within the tube 63 makes possible any shape of chamber C desired while the tube is an economical shape to withstand internal pressure. If it is found advantageous to utilizeypressures` above those safe for commercial tubes, the washers can be made a loose nt in the enclosing tube and compressed along its axis to form an inner tube. The leakage between the washers may vent through the clearance between the. washers and outer tube and so relieve the latter of a part, or substantially all of the stress.

The effectiveness of the fuse may be increased by providing means to increase thel intimacy of contact between the arc and the wall structure of chamber C; for example, as shown in Fig. 7, there may be provided plates 65 of magnetic material so disposed that they tend to draw the arc towards the convergence of the central opentheir flux moves the arc toward a convergence of chamber C. The latter arrangement without the fuse wire is suitable for a lightning arrester by using the choke coils of the arrester for coils 66, tov force the arc against the wall structure for liberation of chilling gases. In this case the conventional gap is inside of the tube and a gap adjustment may be provided.

In the modifications shown in Figs. 10 and 11, the tube 63 is omitted, and the washers 61 forming the chamber C are made with the portion between the outer diameter and the chamber sufcient in extent to withstand high pressures. The washers are clamped by insulated bolts 66 which extend through openings 69 therein between the terminal caps l0, 'ii of the fuse or arrester. The washer openings may be similar punchings and may be alternately reversed or rotated in assembly so that the peripheries of adjacent washer openings do not coincide (as shown in Fig. 10) to form a chamber C having alternately along the wall thereof ridges a and peck--l ets b. Since the sides of each of the laminations or washers 6l overlap separated portions of the openings of adjacent laminations, two pockets b are formed between opposite sides of each lamination. In this manner a greater numberI of ridges and pockets are formed for a given number of laminations than in the case of the laminations shown in Fig. 17, more specifically referred to hereinafter. The pockets b permit raing, or as shown in Figs. 8 and.9, coils 66 may be disposed adjacent the fuse and so connected that dial expansion of the gases with consequent radial velocities enhancing the penetration of the arc by the chilling gases. The arc may be forced toward the convergences a, as by coils 66, by magnetic plates 65, or by any suitable arrangement. A simple oval-shaped tube may be made by aligning the oval opening of the discs used in Fig. 10.

The modiflcation shown in Figs. 12 and 13 are in general similar to Fig. 11, except that lateral vents l2 are provided by interposing spacers 'i3 (Fig. 13) between the washers 61. A circuit may be established through the bolts 68 to produce a field for forcing the arc toward one of the walls.

In the modication shown in Figs. 14 and l5, lateral vents 16 extending in two directions from the chamber C are provided by separating the laminations with spacers l5. The spacers and/or the bolt on the side near the convergence may be of Amagnetic material, suitably insulated, to produce a field for forcing an arc toward the convergence. In common with the other fuse con-"l structions shown, the arc whether large or small is immediately quenched by liberation of the gases from the material -on or comprising the washers by action of the arc.

The invention may also bev utilized to relieve the dielectric strain of high tension insulators, such for example as the umbrella type of insulator shown in Fig. 16 or a different type of insulator as shown in Fig. 17.

Referring to Fig. 16, the internal construction of an insulator 46 of the umbrella type is shown. A stack of washers or laminations 5l of the aforesaid suitable insulating material, with openings to form a chamber. C, are disposed within the longitudinal passageway or bore of the insulator body. The washers may be of any one or more of th types shown in Figs. 3 to 6, 10, or 12, etc. The lug 52, which threadably engages the base member or cap 53 of the insulator to clamp the washers in place, is provided with a passage 54 incommunication with chamber C and opening to atmosphere through lateral vents `55.

When under abnormal conditions, as during electrical storms, the potential across the insulators tends to assume excess values, the dielectric resistance of the path within the insulator between plug 52 and the supporting member 56 breaks down andan Varc is formed between these members relieving the dielectric strain upon the insulator. Under the influence of the arc, the washers 5| liberate a large volume of chilling gas which extinguishes the arc. As shown, the holes in alternate plates or washers 5| are of different diameters, forming `recesses y or pockets which produce violent gas turbulence, eddies or lateral velocities in the gases to promote and augment penetration of the chilling gases into the arc stream. The volume of chilling gas may be somewhat increased by'making one or both of the arc terminals of gas liberating conductor; for example. the tip 51 may be` of carbon.

The gases issuing from the vents 55 are so directed that they do not affect the dielectric strength of the insulator below. A grading ring or other means known to the art for equalizing the potential difference across the insulators, may be used.

The opening in the washers may be small, for

I' development of very high lgas pressures with the result that the devicehas high k. v. a. rupturing capacity for relatively short length of chamber C. The walls of the chamber can withstand high pressures because of the reenforcement provided by the thick hub of the insulator. The respective caps of the insulator includingplug 52 form closure members for opposite ends ofthe arc extinguishing chamber.

As stated above the washers or laminations within the bore of the insulator body may be of any of the types illustrated, the plug 52, as shown, being large enough in diameter to permit, when the plug is removed, assembly of the laminations within the insulator or their removal therefrom, without removing the metal cap of the insulator. In Fig. 1'7, the invention is shown-applied to a different type of insulator. The description of Fig. 16, in general, applies to this modification and need not be repeated. The metal caps are constructed so that the surfaces presented to each other are each substantially part of the surface of a sphere for an improved discharge characteristic under conditions of excessive potential difference. The caps may b e provided with arcing tips of any desired form or material. As indicated, the plug 52 for Vsecuring the stack of washers in place may be solid, i. e., without a vent 55, so that during discharge a high pressure will build up to aidl in extinguishment of the arc. This is permissible as the insulator body is capable of withstanding high internal pressures.

Where the lateral vents are' desired, the plug 52 of Fig. 16 may be substituted furthe, solid plug of Fig. 17. For example, in Fig. 18 the insulator unit of Fig. 17 is shown with a plug 52 having lateral vents 55. The laminations or washers 61 within the body of the insulator are of the type shown in Fig. 10. Asabove described the laminations are by plug 52 pressed together to prevent radial ow of gases between the laminations. At least one ridge a and one pocket b is formed between op- Iposite surfaces of each lamination.

Within the chamber C, the resistance of the discharge path is increased due to the generation of gases and the high pressure, as above described. After the arc is extinguished, the device is at once capable of again functioning to take care o! another discharge.

The arc may tend to carbonize the edge of the washers having the smaller diameter hole without appreciable effect on the overall dielectric strength as the recesses between the washers prevent carbonization of the washers having the larger diameter hole.

In all forms of the inventiomthe washers or plates are preferably made of material `Vwhich upon contact with an arc liberates a gas or gases' which chill the arc to extinction and prevent it from reforming; for example they may be of fibre, etc., which release hydrogen and/or carbon dioxide when engaged by an arc, or they may be made of other material fcoated or impregnated with gas-producing chemicals, for example, boric acid. In general, the gases best suited have high specific heat 'and low density as hydrogen, water vapor, etc. Certain chemicals release powerfully effective gases when subjected to an arc but lose their dielectric strength. With the stacked plate construction, it is possible to use such materials, as ammonium alum, and maintain proper dielectric strength for the stack by alternating plates. containing or coated with the aforesaid -type of chemical, with other plates which retain Vtheir dielectricl strength when subjected to an arc l While I have illustrated several speciiic types of arc-extinguishing devices, it is to be understood that my invention is not limited thereto but is commensurate in scope with the appended claims.

What I claim is:

1. In an insulator unit provided with a bore through the body thereof, means for relieving the dielectric strain of the insulator comprising a stack of transverse pressure withstanding laminations within the insulator body, a preponderant number of which are formed of insulating material of a character which when subjected to van arc liberates chilling gases, openings in said laminations to form through the central portion of the stack an arc extinguishing chamber, the sides of each lamination overlapping a portion of the'-Y openings of adjacent laminations to form between opposite surfaces of eachlamination at least one ridge and at least one pocket, closure means for the respective ends of said chamber cooperating to press said laminations tightly against each other, and a laterally extending-vent at the lower end of said insulator.- the gases generated within said arcing chamber flowing axially of said chamber and discharging through said laterally extending vent.

2. Thelcombination with an insulator unit proi vided with metal caps secured to opposite ends thereof, said insulator being provided with' an opening forming an arc path between said caps,

of a stack of laminations of insulating material mounted within said opening, said material when subjected to an arc liberating chilling gases, said laminations having openings at their central por- .tions to form an arcing chamber of restricted volume between said metal caps, the inner edges of the openings of adjoining laminations being disposed to form alternate ridges and pockets to plug including a lateral vent discharging the gases 75 of said laminations at right-angles to the longitudinal axis of said passageway, the inner edges of said openings forming an arc extinguishing chamber, metal caps supported on said insulator unit at opposite ends of said passageway, said metal caps being formed to present convex surfaces toward each other, arcing terminals located at opposite ends of said chamber and respectively electrically connected to said metal caps, a preponderant number of said laminations being formed of an insulating material which when subjected to an arc liberates chilling gases, said laminations being disposed to form alternately ridges and pockets along the longitudinal wall of said arc extinguishing chamber to produce throughout the length of said chamber localized gas turbulence to introduce chilling gases into the arc at a plurality of points, and means for pressing said laminations together to prevent radial flow of gases between said laminations.

4. An arc extinguishing device comprising a plurality of laminations a preponderant number of which are formed of an insulating material of a character which when subjected to an arc liberates chilling gases, each lamination having an opening to form in conjunction with the openings of the other laminations an arcing chamber, adjacent laminations being disposed to form aiternately ridges and pockets along the longitudinal wall of said arcing chamber, means for applying an axial pressure to said laminations to hold their outer closed peripheries tightly in engagement one with the other thereby to prevent radial flow of gases from said chamber, a conductor mounted at one end of said chamber to close said end of said chamber, a second conductor, means for supporting said second conductor at the opposite end of said chamber, said ridges and pockets when an arc is drawn between said conductors acting to produce localized gas turbulence to introduce into the arc at a plurality of points said chilling gases, and a passageway of restricted cross-sectional area extending from one end of the chamber and locatedv adjacent said second conductor for axial flow of gases within said chamber.

5. An are rupturing device comprising a tubular extinguishing chamber defined by duplicate laminations of insulating material disposed with their planes substantially normal to the arc and,

having openings forming continuous walls for said chamber, the sides of each lamination overin a lateral direction with respect to said opening lapping a portion of the openings in the adjacent A laminations to form between opposite surfaces of each lamination at least one ridge and at least one pocket, said pocket being in communication with but extending radially from said chamber.

x6. An arc rupturing device comprising an arc extinguishing chamber defined by duplicate laminations of insulating material disposed with their planes substantially normal to the arc and having openings forming continuous walls for said chamber, the sides of each lamination overlapping separated portions of the openings in the adjacent laminations to form between opposite surfaces of each lamination a pluralityof ridges, and a, plurality of pockets, said pockets being in communication with but extending radially from said chamber.

between opposite surfaces of each lamination at least one ridge and at least one pocket, said pocket being in communication with but located to one side of said chamber, and means including a conductor for closing one end of said chamber, means including a second conductor for closing the opposite end of said chamber, said last mentioned means including a vent for axial iiow of gases through said chamber, said ridges and pockets introducing turbulence in the flow of the gases to augment the cooling and extinguishment Aof the arc formed between said conductors.

8. In an Vinsulator unit having a bore through the body thereof and metal caps secured to opposite ends thereof, the combination of a stack of' laminations formed of insulating material within the insulator body, said laminations having openings forming an arc extinguishing chamber Within the bore of the insulator, the sides ofieach lamination overlapping a portion of the openings in the adjacent laminations to form between opposite surfaces oi.' each lamination at least one ridge la'nd at least one pocket, each pocket being in communication with but extending radially from said chamber, and a vent at one end of said insulator, the gases generated within said chamber owing axially of said chamber and discharging through said Vent.

HERBERT GRAVES. JR.

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