US2620452A - Expulsion type arrester - Google Patents

Description

Dec. 2, 1952 c. wxPETERsEN 2,620,452

' ExPULsIoN TYPE ARRESTER Filed sept. ze, 1951 2 4:sans:Ts--SHLET 2 25d INVENTOR.

Hilorn ery Patented Dec. 2, 1952 UNITED ISTA'ITES PATENT OFFICE IEXPULSION .TYPE ARRESTER Clifford W.`.Petersen, Wauwatosa, Wis., assignor to'M'c'Graw'Electric Company, Milwaukee, Wis.. a'corporation of Delaware Application.Septemberf26, 1951, Serial No..248,337

7 Claims.

ent No. 2,429,533, granted to Herman O. Stoelting,

on October 21, 1947 and assigned .to the assignee of the .present invention,.andconstitu-tes a novely improvement over that patented structure.

Ellective operation rof an vexpulsion type lightning arrester depends upon its: ability .to .produce .copious yquantities -of arc-extinguishing gases .at a ,pressure -sufficient :for .blocking .follow current while concurrently providinga relatively cool and yde-ionizing .atmosphere for -quenching conductive arc-sustaininggases Itis, therefore, ageneral object-.of the presen-t invention to .provide a novelexpulsion .tube vfor lightning .arresterswith .a bore .in the natureof a cone having its .apex positioned to `provide a constricted cross section proximate to the upper electrode and gradually aring downwardly towards the lower electrode, thereby to provide an expulsion arrester with relatively confined portions for extinguishing low-current arcs, in addition to providing a chamber capable of evolving copious quantities of arc-extinguishing-gases for quenching high-current arcs and effectively blockingfollow current. 1

A subordinateobject of this invention is to provide a novel expulsion tube for lightningarresters which utilizes a flared or tapered bore cross section in which the crosssection may take any one of -a number of forms Aproviding a narrowly constricted portion, or portions, defining a relatively distended portion.

Referring now to the drawings which accompany this specification:

Fig. 1 is a longitudinal view, partially in sec'- tion, of the expulsion-type arrester depicting the Vpreferred embodiment of 'the present invention.

Fig. '2 is a cross#se'ction 'taken'along lines 2-2 of Fig. 1.

Fig. 3 isa cross-section taken 'along lines 3-3 of Fig. 1;

Fig.' 4 is a perspective view of a semi-cylindrical half-portion of the novel expulsion tube.

Fig. 5 is an 'end view vof another form ofthe novel yexpulsion tube.

Fig. 6 ls a perspectiveview of another embodiment of a half-portion of the vnovel `expulsion tube.

Fig. '7 is an end Viewviof a 'further embodiment of the novel expulsionA tube.

y( Cl. 313-) Fig. 8 is an end view ofstill another embodiment of the novel expulsion tube.

.Referring particularly to Fig. 1, the .preferred embodiment-constitutes a vhousing I of dielectric material-usually porcelain-having a Achamber 2, which is nearly coextensive lengthwise with the housing and open at the lowerend, and closed at the upper endvexcept for an aperture 3, which aperture accommodates a stud 4. The .stud fis electrically connected to-a washer 5 makingcontact with .an elongated electrode member 6 clamped to the lower end-of a petticoat insulator l. The insulator II is anchored to the upper end of the stud 4, which is rmlyembedded therein.

A line terminal 8 4is fastened to the upper extremity ofthe insulator 1, and is adapted to engage a-conductor wire connecting with the power line that is to be protected. An electrode I9 is secured to the upper'end-of the insulator I mak ing electrical contact with the terminal member 8 .concurrently serving yto hold this electrode member in operating position. An open-spark gap I 0 is formed by the spacing of the free ends of both electrode members 6 and 9. Though an open spark-gap arrangement is preferable, it -is within the province of this invention to provide internal spark-gap electrodes (not shown). The spark-gap does not constitute a part of thepresent invention, but is necessary for isolating the novel expulsion tube from the line terminal 8, thereby preventing .leakage currents from flowing to ground through the expulsion tube and associated parts.

A gasket II may be provided as a clamping cushion between the insulator 'I and the housing y member I to prevent chipping of the porcelain when the `parts are drawn together. This gasket also acts as a moisture-proof seal.

The components shown assembled within the chamber 2 include a metal electrode plug I2. The plug I2 is threaded externally to engage with a complimentary internally threaded tubular retainer member I3 made of nsulatingmaterial, preferably horn liber. The tubular retainer member I3 is reinforced by a, metal sleeve I4 surrounding that-member,the upper end of which is at a plane approximately level with v'the plane of the lower extremity of the plug I2. The :fiber tubular retainer member I3 is preferably eX- tended above the plug I2 to provide 'a chamber I 3a, which chamber provides a convenient means for increasing the ashover distance between the plug and the sleeve I4, thereby conning the :arc within the novel expulsion tube hereinafter described, where it may be properly extinguished.

.The lower end of .the lretainer member I3 is externally threaded to engage a flanged fitting I5, which serves concurrently as a closure for the chamber 2, as a support for the novel arc-extinguishing tube hereinafter described, and as a lower terminal member to which a ground wire (not shown) may be connected. A gasket IB is provided between the porcelain housing I and the fitting I to act as a cushion for preventing breakage or chipping of the porcelain.

The metallic tting I5 is provided with a discharge port Il for releasing gases to the atmosphere. A lower washer-like electrode member I8 is positioned concentrically of the gasket I6 and in electrical contact with the tting, I5. The fitting is also provided with a means for connecting the arrester, with ground shown here asV a solderless connector in the form of a bolt I9 engaging a complementary threaded opening in the fitting I5. The substantially at surface area 2@ of .the tting serves to support the novel expulsion'tube as hereinafter described.

The preferred embodiment of the novel expulsion tube will be described with reference to Figs. 1, 2, 3, and 4. The novel expulsion tube 25 is preferably of horn bre or equivalent arcextinguishing material, and is preferably split longitudinally to form two semi-cylindrical halfportions 25a and 25D, respectively, which are held together by the tubular retainer member I3. At the upper end of the expulsion tube, preferably 'in contact with the plug I2, and gripped between the two half-portions 25a and 25D of the expulsion tube, is acylindrical metal insertV 26 which serves as a spark and arc electrode.

The tube 25 has an expulsion chamber consisting of `a slot-like passageway trending downward-l 4 upper electrode 26 originates at a very restricted portion 3l of the expulsion chamber, proximate to the apex of the semi-conical passageway 30. Thus, even the smallest amount of gas created will set up a considerable pressure almost instantly because of the area restriction. This pressure creates a very dense gas which serves to block the flow of follow-current. Thus, pressures built up by the surge alone should be suicient to prevent follow-current. The relative slowness of the gas movement towards the discharge end will maintain a pressure for a suicientlength of time to prevent follow-current from starting until the arc has been properly extinguished. The arc, moving towards the ground connection, will follow a constricted path-the narrowly constricted edge portion Sila. Pressures built up here tend to blow the arc towards the center of the passageway where they will be cooled very rapidly. Thecooled, de-ionized gasesrwill then be expelled from thev expulsion chamber through the discharge port I7. Since the extinguishing gases created by action of the arc The cross-section of half-portion 25hl is shown in Referring Vnow to half-portion 25a, the slot-like expulsion chamber or passageway 30 provides a cross-section that gradually lares downwardly as shown in Figs. 1 and 4 from a relatively constricted portion 3l connecting with the lower extremity of the electrode 26 to the relatively distended portion 32 connecting with the discharge port I'I. The are is preferably semi-conical in nature; viz, providing a gradually increasing depth as well as a gradually increasing width intermediate of its end portions 3| and 32, respectively. From an examination of Fig. 4 it will beseen that the cross section configuration is approximately sectorial-and is narrowly constricted along one edge portion and considerably distended along the opposite edge portion. The narrowly constricted edge portion is identified by reference numeral 30a, whereas the distended portion of the passageway is identified by reference numeral 30h. The configuration takes substantially the same form as the configuration of one of thehalf-portions disclosed in the above mentioned patent granted to H. O. Stoelting, over which thepresent invention rconstitutes an improvement; Y

It v,will be apparent thatan arc forming at the on the horn libre is directed downwardly towards theendsupported by the fitting I5 the gases will be expelled at a place where the arrester is me chanically strongest.

Referring now to Fig. 5,- it will be apparentl that an effective expulsion tube may consist of two substantially identical half-portions 25a and f 25C, ,which are constructed in left and right hand relationship.v The arc passageway 35 provides-a sectorial cross section vwhich gradually .ar'es downwardly from the electrode 2E towards the lower discharge end of the novel expulsion tube as viewed in Fig. 5. As was stated above, it is preferable to slot each of the half-portions 25a and 25e to provide a vgradually increasing depth as well as width. This particular structure may be provided where it is desired to have van arc passageway that provides a relatively larger gas` discharge portion in substantially the same length tube as suggested by the preferred embodiment.

' Another embodiment of the novel lightning arrester expulsion tube is shown in Figs. 6 and 7,

wherein a novel half-portion 25d is mated withA a half-portion 25h Ypreviously described. The

novel half-portion 25d includes an arcing slot or passageway 36 having a cross-section in the nature of a half-round or semi-elliptical which is particularly shown in the end view, Fig. 7. The l half-round passageway, like the sectorial'pas sageway of the preferred embodiment, graduallyiiares vdownwardly from the lower extremity (of the electrode 26 tothe Vdischarge portioncon-- nected to the lower electrode I8. Again, the passageway 36 preferably takes the form of a semi- Y conical chuteA providing a relatively constricted end.

Y stricted edges 36a and B'ub are provided. with a distended portion 38 intermediate thereon- The structure illustrated in Fig. 7 utilizes two half-portions 25h and 25d to provide al cylindrical A expulsion tube which may be positioned in-the tubular retainer member 3l and intermediate of the plug I2 and the lower` electrode I8. ,The insert 26 1s gripped between the mating halfportions at the upper end making electrical con?.

...tact with the metallic plug I2.

A further embodimentis' illustratedjin Figll and :is .provided by'mating two :substantially iden ticalhalf-portions 25d. Obviously, this is a less expensive structure from a manufacturing standpoint,` inasmuch 'asv the mating half-portions 25d d not have to be in left or right vhand relationship as the half-'portions 25a and 25e-of the structureshown in Fig. 5.

All ofthe vabove described vembodiments operate in substantially the same manner, and the mode of operation will be ldescribed with reference to the preferred embodiment disclosed in Fig. l. When a surge occurs on the power line and is of high enough potential, it will simultaneously spark-over the external gap l0 and the internal expulsion gap between the arcing electrode 26 and the lower electrode I8 which is electrically connected with ground through the fitting l5.

Under certain conditions the surge may initiate the flow of power follow-current making it necessary to extinguish the power follow-current arc in order that the arrester may return to its original operating condition. To accomplish this, this invention contemplates the use of the novel expulsion tube described above and contained within the retainer member I3 and extending laterally between the electrode plug l2 and the lower electrode I8. The power current, which is normally7 60-cycle current, produces an arc that tends to follow the path taken by the abnormal surge voltage that has sparked over the arrester electrodes, and will tend to be coniined to the relatively constricted portions of the passageway 30a where the pressures built up will limit, cool and rapidly extinguish this follow-current at first current zero.

The novel flared passageway provided by this invention makes use of an expulsion gap that requires no intermediate electrodes, but operates to effectively block power follow-current and extinguish arcs produced by surge voltages of both very low and high magnitudes. As was described in the above mentioned patent granted to Stoelting, a passageway configuration providing both a relatively constricted portion and a distended portion serves to provide an initiating means for arcing at the constricted portion wherein the erosive action of the arc is conned to the distended portion where it has the least effect towards terminating the useful life of the expulsion tube. In addition, the present structure provides a further constricted portion at the arc initiating area proximate to the electrode 26 where relatively low current arcs may be immediately extinguished, at the same time providing an eiiective blocking means to follow-current, while high magnitude arcs may be effectively extinguished in the relatively distended portion approaching the discharge end of the passageway after initial spark-over along the constricted edge of the passageway.

I claim:

1. A lightning arrester of the expulsion type including, two spaced electrodes, an expulsion tube intermediate said electrodes, said tube embodying gas evolving material defining a chamber tapered longitudinally between said electrodes and providing a constricted aperture adjacent one electrode and a distended aperture adjacent the other electrode, whereby back gas pressure in said chamber is effective to extinguish arcs and concurrently block current following either high or low magnitude arcing between said electrodes.

2. A lightning arrester of the expulsion type including, two spaced electrodes, an expulsion tube intermediate said electrodes, said tube embodying gas evolving materialdening a chamber tapered longitudinally between said electrodes and providing a constricted aperture Aadjacent one electrode and a distended aperture adjacent the other electrode, the transverse cross-section of said chamber being an aperture of elongated slot-like configuration, said chamber vbeing narrowly constricted widthwise substantially throughout .its length on at least one portion of its cross-sectional area, andicomparatively ldistended widthwise substantially throughout its length at. a portion of its .cross-sectional area laterally of the first mentioned portion, whereby back gas pressure in said chamber is effective to extinguish arcs and concurrently block current following either high or low magnitude arcing between said electrodes.

3. A lightning arrester of the expulsion type including, two spaced electrodes, an expulsion tube intermediate said electrodes, said tube embodying gas evolving material and defining a chamber tapered longitudinal between said electrodes and providing a constricted aperture adjacent one electrode and a distended aperture adjacent the other electrode, the taper of said chamber havingT a major dimension as measured transversely to the longitudinal axis of said chamber and a minor dimension substantially normal to said major dimension, whereby back gas pressure in said chamber is effective to extinguish arcs and concurrently block current following either high or low magnitude arcing between said electrodes.

4. A lightning arrester of the expulsion type including, two spaced electrodes, an expulsion tube intermediate said electrodes, said tube embodying gas evolving material and dening a chamber extending between said electrodes, said chamber having an elongated cross-sectional delineation including an apex at one end of the elongation and a relatively wide base portion at the other end, said chamber being tapered longitudinally between said electrodes, whereby back gas pressure in said chamber is eiective to extinguish arcs and concurrently block current following either high or low magnitude arcing between said electrodes.

5. A lightning arrester of the expulsion type including, two spaced electrodes, an expulsion tube intermediate said electrodes, said tube embodying gas evolving material and dening a chamber extending between said electrodes, said chamber having an elongated transverse crosssection extending substantially through its length, one side of said chamber being a fiat surface and the other side being grooved to provide an apex at one side of said cross-section and a relatively distended portion at the other side, said chamber being tapered longitudinally between said electrodes, whereby back gas pressure in said chamber is effective to extinguish arcs and concurrently block current following either high or low magnitude arcing between said electrodes.

6. A lightning arrester of the expulsion type including, two spaced electrodes, an expulsion tube intermediate said electrodes, said tube embodying gas evolving material and defining a chamber extending longitudinally between said electrodes, said chamber having a transverse cross-section extending substantially through its length and defining a substantially elliptical aperture including two opposed constricted portions and a relatively distended portion intermediate said constricted portions, said chamber being` tapered longitudinally between said electrodes, whereby back gas pressure in said chamber is eifective to extinguish arcs and concurrently block current following either high or low magnitude arcing between said electrodes.

7. A lightning arrester of the expulsion type including, two spaced electrodes, an expulsion tube intermediate said tube embodying gas evolvingmaterial and defining a chamber extending between said electrodes, said chamber having an 10 elongated transverse cross-section extending substantially through its length, one side of said chamber being a iiat surface and the other side being grooved tojointiy provide two opposed constricted portions with said flat surface and a'relatively distended portion intermediate said constricted portions, said chamber being tapered longitudinally between said electrodes, whereby back gas pressure in said chamberis effective to extinguish arcs and concurrently'block current following either high or low magnitude arcing between said electrodes.

` CLIFFORD W. PE'IERSEN.

No references cited.

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