US2012689A - Device for and method of protecting lightning arresters and the like against moisture - Google Patents

Description

Aug. 27, 1935. J R, McFARLlN 2,012,689

l DEVICE Fon AND METHOD oF PRo'IEc'rING LIGHTNING ARREsTEns AND 'rx-m LIKE AGAINST loIs'rURE Filed lay 22, 1955 *a 2e as A TTORNEY.

Patented Aug. 27, 1935 DEVICE FOB AND METHOD 0F PROTECTING LIGHTNING ARRESTERS AND THE LIKE AGAINST MOISTURE John R. McFarlln, Philadelphia, Pa., assignor to Electric Service Supplies Company, Philadelphia, Pa., a corporation of Pennsylvania Application May 22, 1933, Serlnl No. 672,221

6 Cm (Cl. 173-424) This invention relates generally to lightning arresters and the like and more particularly to a means for and method of preventing the passage of moisture into the arrester via the line lead connecting the arrester to the phase conductor.

In a number of instances it has been found that lightning arresters, while in service, have been the cause of more or less serious radio interference and upon investigating this matter I have discovered that in many cases the disturbing eiect upon radio reception has been due to the presence of moisture within the arrester. Not only has it been found that moisture-laden arresters have been the cause of radio disturbances but also that the presence of moisture Within the arrester sooner or later results in the failure thereof, this being due to the fact that the moisture upon coming into contact with the arrester spark gap electrodes form upon the latter electrically conductive salts of the metal of which the electrodes are formed whereby the gaps between the electrodes are substantially decreased, if not entirely bridged. Also, in that type of arrester wherein in addition to the air gaps other characteristic elements are employed, such as a discrete crystalline conductive mass, or bonded conductive material in the form of rods, plates or blocks, or other conductive material possessing the required characteristics for use in lightning arresters, the presence of moisture within the arrester eventually ail'ects the characteristic element to such extent as to interfere with the normal operation of the arrester, if not to render it wholly inoperative, this being primarily due to the fact that when the characteristic element of the arrester is moist a definite electrically conductive current leakage path is provided by which current may freely pass through the arrester. The current leakage paths so produced by the moisture present within the arrester not only give rise to the frying effect which is so disturbing to radio. reception but also render the arrester incapable of performing with maximum efliciency its intended functions.

Inasmuch as in practically all arresters the interiors thereof are effectually sealed against the deleterious effects of the elements, the most probable way for moisture to enter the arrester is by way of the conductor or conductors leading to the electrode terminals of the arrester. In certain installations the arresters are so mounted that the upper end thereof is below the power line to which it is connected and in such instances it will be apparent that if the insulation of the arrester line lead is defective or ii the connection between the line lead and the power line is not completely moisture-proof, water will enter the line lead and will flow downwardly through the stranded wires thereof and into the body of the arrester. On the other hand, in those instal.- lations where the line-lead connection to the arrester is above the line lead connection to the power line, water can still enter the arrester upon being gradually absorbed by the paper, cloth or other serving on the line lead with the result that it reaches the conducting wires thereof and through the latter is conducted into the body of the arrester; or by capillary attraction the water` may dnd its way into the arrester via the stranded wire core of the line lead; or by suction caused by a rapid chilling of the air within the arresteras by a rain storm occurring on a hot day-moisture present in the stranded core of the line lead may be drawn into the arrester body.

While the foregoing possibilities of moisture entering the interior of the arrester body might be lessened, if not entirely avoided, by moistureproofing the connection between the line-lead and the power line and by providing a moisture-proof insulating coating for the line-lead, it has been found that even the highest type of moistureproof connections and conductor insulations eventually deteriorate in use to such extent that they no longer exclude the passage of water or moisture therethrough. Furthermore, practicalexigencies demand the use of mechanical connections between the line-lead and the power line as cannot be conveniently taped or otherwise rendered moisture proof and such connections by their very nature afford a principal inlet for water to travel via the line lead into the arrester.

From the foregoing it will be seen that the remedy for preventing the passage of moisture into the interior of the arrester, to be permanently effective, must consist in some other expedient than that of rendering temporarily moistureproof the line-lead insulation and the connection between the Ime-lead and the power line. It is to provide this permanently effective expedient that the present invention has been developed, it being among the objects of the invention to provide a means for and method of permanently and eifectually precluding the possibility of moisture entering the arrester via the lead line which connects the arrester to the phase conductor or power line.

A more specific object of the invention is to provide in a lightning arrester or the like, a moisture resisting cap which is adapted to be secured to the arrester end of the line lead in such manner that moisture which might reach said cap `vis. the stranded wire core of the'line lead will not only be prevented from entering the arrester /but will be directed outwardly therefrom instead,

thus insuring against the entry of moisture into the body of the arrester and at the same time providing a deilnite outlet for any moisture or water which may have found its way into the line lead.

Other objects of the invention and advantages resulting therefrom will be apparent more fully hereinafter.

The inventionV consists substantially in the combination, construction, location and relative arrangement of parts, all as will appear more fully hereinafter, as shown in the accompanying drawing, and as finally pointed out in the appended claims. In the said accompanying drawing:-

Figure 1 is a vertical sectional view of a lightning arrester assembly wherein the line lead connected thereto is equipped with a moisture resisting cap constructed and arranged in accordance with and embodying the principles of the present invention;

Figure 2 is a side elevational view of the upper terminal member of the arrester showing the cap-equipped line lead connected thereto as well as the device employed during the operation of sealing the arrester hood in position for producing the desired moisture outlets in the outer extremity of the moisture resisting cap;

Figure 3 is a vertical sectional view of the arrester line-lead as equipped with its moisture resisting cap;

Figure 4 is a sectional view taken on the line I-l of Figure 2; and

Figure 5 is a vertical sectional view of an arrester of the protective gap type showing a modified form and arrangement of means for preventing the passage of moisture into the interior of the arrester via the conductors connected to the electrode terminals thereof.

Referring now to the drawing, it will be observed that the invention has been illustrated in its application to two different types oi' lightning arresters, one such type being shown in Figure 1 and the other in Figure 5. The principles of the invention, insofar as respects means for and method of excluding the entry of moisture or water into the interior of the arrester body, is

the same in each case, and it will be understood,

that the invention is applicable to other types of lightning arresters and the like than those herein illustrated and to other electrical devices wherein the presence of moisture within the interiors thereof is desired to be prevented. Referring now more particularly to that type of lightning arrester the upper portion of which is shown in Figure 1, it will be observed that it comprises a non-conducting substantiallyv cylindrical casing or main body portion I0, usually of porcelain, upon the top end of which is provided a metallic closure cap II, constituting the upper terminal member of the arrester, this member II being arranged in overlying relation to an electrode supporting plate Il. Suspended from the central point of the plate II are a plurality of vertically spaced pairs of dished spark gap electrodes I2, each pair of these electrodes being maintained in predeterminedly spaced relation by the respective insulators I3. 'I'hese insulators I3 and the electrodes I2 are maintained in the assembled relation shown by an insulating tie rod I4. The upper end of the arrester assembly is further provided with a porcelain cap II which is preferably secured in place by means of a sealing compound Il introduced into and illling the space between it and the exterior of the casing I0. It is believed that the foregoing description of the lightning arrester shown -in Figure 1 will be suillcient for the purposes of explaining the present invention. Should further information be desired respecting the details of construction and operating characteristics of this type of arrester, reference is made for such additional information to my earlier letters Patent No. 1,763,- 667, granted June 17, 1930.

As has been previously set forth, and as will be apparent from an examination of the arrester construction shown in Figure l, the most probable way for moisture to enter within the interior of the arrester body Il, assuming that the hood or cap I5 has been properly sealed to the body Il, is by way of the line lead connecting the terminal cap II of the arrester to the power line or phase conductor (not shown). Heretofore and prior to this invention the arrester end of the line lead has been soldered or otherwise secured to the depending flange Il of the terminal cap II, the said end of the line lead being stripped of its insulation to afford the desired metallic contact' between the conducting core of the line lead and the terminal cap I I. It was found that when the bared end of the line lead was so connected to the terminal cap II of the arrester, any moisture which found its way into the interior of the line lead eventually passed via the line lead into the interior of the arrester body, this being due to the fact that no provision was made for preventing the free passage of the moisture beyond that end of the line lead which was connected to the terminal -cap II of the lightning arrester. Not only does the presence of the moisture within the interior of the arrester seriously affect its normal operation, but also in those instances wherein the bared end of the conductor is soldered to the terminal member of the arrester it has been found that moisture reaching the soldered connection combined with the soldering ux to such extent that corrosion was set up, this corrosion tending to creep into the interior ofthe arrester with the result that the electrodes eventually became corroded, thus causing failure of the arrester. It is to prevent the passage of moisture or water beyond the end of the conductor which is connected to the arrester terminal and thence into the interior of the arrester body and to prevent the moisture from reaching the soldered connection between the conductor and the arrester terminal that the present invention has been developed and the means for and method of attaining this objective will now be described.

In carrying out the invention, the arrester end of the line lead Il which connects the terminal cap II to the power line or phase conductor (not shown) is stripped of its insulation whereby to expose the conducting core 2B of the line lead (see Figure 3). The bared end 20 of the line lead is then provided with a drawn copper sleeve 2i the outer end of which is closed, as at 22. Preferably, this sleeve is drawn from a copper disc and is of such length that the open end 2l thereof flts over and embraces the insulation 2l of the line lead. The bared end 20 of the line lead is clamped within the sleeve 2 I, a substantial portion of the body of the latter being flattened in this clamping operation as shown more particularly in Figures 2 and 3. 'I'he open end of the aoiaeee preferably completed before the terminal cap Ii is operatively secured'to the arrester body il. Afterthe terminal cap il islocatedinpositionas shown invFigure I. the porcelain cap or hood il of the arrester is secured in the position shown by the use of the sealing compound Ii which is introduced within the annular space formed between the outer surface of the body il and the inner surface of the hood II. In filling this annular space with the sealing compound, the latter is poured to a depth that preferably covers the enlarged end of the sleeve Il. In order, however, tomaintainclearthespaceorspacesllbetween theinsulationofthelineleadandtheportionof the sleeve which embraces said insulation, a device is employed of the character shown in Figure 2, this device, designated generally by the reference numeral 21, being in the form of a tool having a `pair of spring-pressed prongs 2l the sharpened extremities 2l of which are respectively inserted within the spaces 25-25 aforesaid (see Figures 2 and 4). The prongs 20--20 are soinserted int/J the spaces 25-25 aforesaid just before the sealing compound is poured into the space between the bodv il and the hood It, the prongs being withdrawn only after the sealing loompound has hardened, it being apparent that when the prongs are thus removed one oi' more outlets are provided which communicate freely with the space surrounding the baredend of the line lead embraced within the sleeve 2 I Prom the foregoingitwillbe apparentthatanymoistureorwater which might travel through the line lead toward the sleeve equipped end thereof will be prevented from passing into the interior of the lightning arrester by the sleeve 2l and will instead be dlrected outwardly from the interior of the sleeve through the outlets provided in the manner Just described.

InFigurethereisiilustratedanothertypeof electrical protective device known as a ground gap. In this type of device it is also desirable to provide means -for excluding the possibility of moisture entering the interior thereof because suchmoisturewill eventuallyestablish undesirable current leakage paths across the gap Il formed between the spaced electrodes Il and I2. In this type of device wherein the electrodes ll and 32 are respectively provided with terminal elements 33 and 34 the conductors I5 and 3i are respectively connected to the terminal members by means of the conductor terminal sleeves I1. 'Ihese sleeves 31 are each provided with axially extending sockets 38 within which the bared ends of the conductors 35 are projected. Preferably, the bared ends of the conductors are permanently secured within the terminal sleeves by crimping the latter, as at 39, or by soldering, if desired. 'Ihe outer endoftheterminalsieevesocketisenlarmas atlltofreelyreceivetheinsulatedportionofthe eonductor.theinternaldiameteroftheenlarged portionlloftheeonductorreceivingsocketbeing llishtirgreaterthantheexternaldiameterofthe insulated portion of the conductor embraced therewithin,thus pmvidingaspacebetweenthe externalsurfaeeoftheinsulationoftheconducwrlandtheinternalaurfaceoftheterminal aleeveembracingthesame.

Theinnerendsoftheterminalsleeves I1 are permanentlysecured.asatli.totheterminal members Il and ,of the ground gap device. 'lheelectrode assembly. which includes the terminal sleeves l1 and the conductors connected to thelatter,issecuredwithintheinsulatingbodyi2 'ofthedevioebymeansofasealingcompoimd.

`.Inpouringthisaealingcompoundintothebody ,itwiilbeobservedthatthecompoundisiilled to a depth Just short of the outer extremities of the terminal sleeves il-II, thereby leaving clear the space between the insulation of each conductor and the inner wall of its respective terminal sleeve. Any moisture which might pass via either of the conductors Il toward its terminal sleeve I1 will be definitely stopped by the latter and returned outwardly of the ground gap deviceI by way of the space provided between the insulation of the conductor and the embracing portion of the terminal sleeve I1. In principle. the operation of the terminal sleeve as employed in connection with the ground gap device of Figure 5 is identical with that of the terminal sleeve 2| described in connection with the lightning arrester of the type shown in Figure 1.

It will be understood, of course, that the invention is susceptible of various changes and modifications without departing from the general principles or real spirit thereof and it is accordingly intendedtoclaimthesamebroadly,aswellasspe ciiically, as indicated by the appended claims.

What is claimed as new and useful iszi. A method for excludingv the entry of moisture within the interior of a lightning arrester whichconsistsinstrlppingoneendoftheline lead of its insulation. in euuippins the stripped end of the line lead with a fitting having a closed end, inelectricallyconnecting saidilttingtoa terminal member of the arrester, and in providing a passage between the outer surface oi' the line lead insulation and the internal surface of said ntting through which moisture passing viathelineleadtosaidiittingmaybedischarged from the latter.

2. A method of rendering moisture-proof the interior of a lightning arrester which consists in inter-posing a moisture resisting baille between the arrester terminal and the terminal end. of a conductor adapted for connection thereto, in embedding the connection including said moistureresistingbaiiieinasealingcompoundand in providing a moisture discharge outlet leading from the interior of said baille to a point exterior of said sealing compound.

3. In a lightning arrester having a chambered body, in combination with a terminal member thereof disposed within said body, an insulated conductor adapted to be connected to said terminal member, the connecting end of said conductor being stripped of its insulation, a sleeve having one end thereof closed and secured to the bared end of the conductor with the open end of said sleeve extending over the insulation of the conductor and in spaced relation thereto, and means for securing said sleeve to said terminal member whereby said sleeve constitut a moisture resisting baille from the interior oi' which accumulated moisture may be discharged by way o1' the space aiorded between the conductor insulation and the embracing portion of the sleeve, and a sealing compound introduced within said chambered body and embracing said sleeve to seal the chamber against the entry of moisture therein, said sealing compound being arranged relatively to the bame so as not to seal the interior thereof.

4. In a lightning arrester, in combination with a terminal member thereof, an insulated conductor adapted to be connected to said terminal, an electrically conductive sleeve adapted to be fitted over the bared end of said conductor, the outer extremity of said sleeve being closed and the inner extremity thereof being open and arranged in embracing relation with respect to and spaced from the insulated portion of the conductor, and sealing means within which said terminal member and sleeve are imbedded, said means being arranged to provide atmospheric communication with the interior of the sleeve for eiecting the discharge of moisture from within the sleeve outwardly through the open end thereof.

5. In combination with the terminal member ot an electrical device, a conductor, one end of which is adapted to be connected to said terminal member, electrically conductive means adapted to be interposed between said conductor end and said terminal member for interrupting the pasf sage of moisture via the conductor to said terminal member, and sealing means surrounding said conductive means and arranged to permit the free discharge of any such moisture to the atmosphere.

6. In combination with 4the terminal member of an electrical device, a conductor, one end of which is adapted to be connected to said terminal member, an electrically conductive moisture resisting baille interposed between said conductor and said terminal member for directing the passage of moisture outwardly and away from said terminal member, said barile being secured to said conductor and serving as the connecting medium between the latter and said terminal member, means for electrically connecting said baille to the terminal member, and an insulating sealing compound in which said terminal member and baille are imbedded, said compound being arranged) permit the free discharge of the moisture ex'teriorly of the 'said device.

JOHN R. MCFARLDI.

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