US1760983A - Insulator - Google Patents

Description

June 3, 1930. c. s. GORDON ET AL 1,760,983

INSULATQR Filed Dec. 19, 1925 INVENT U. S. Gordom BY JZZowe Patented June 3, 1930 I UNITED STATES PATENT OFFICE CHESTER s. GORDON, or Boomron', AND JAMES r. Lows, or NEwAniz, NEW JERSEY,

ASSIGNORS T AMERICAN TELEPHONE AND TELEGRAPH. COMPANY, A CORPORA TION OF NEW YORK INSULATOR Application filed December 19, 1925, Serial No. 76,505.

This invention relates to insulators, and moisture-proof joint betwen the two units, more particularly .to insulators adapted to and when moisture collects at the joint of the carry more than one conductor. two parts of the insulator, a double leakage In a transmission system such as a telepath to the pin is provided, 'at least for the phone system, it is customary to transpose lower unit, which, of course, results in a conconductors at certain points along pole lines siderable transmission loss.

in order to reduce cross-talk. Where thelines It is. therefore one of the objects of the I are phantomed, it is the practice not only present invention to provide a double insuto transpose the two conductors forming each lator, that is, an insulator capable of carryside circuit but to transpose the pairs of the ing at least two wires, which may be formed phantom as well. In order to do this, it is' of two units supported on the same pin and necessary to provide at the pole-where the having upon the two units interlocking transposition takes place some arrangement joints of such character as to be practically whereby the two insulators carrying two line moisture-proof so that there will be subconductors may be arranged one above the stantially no possibility of a second leakage other instead of horizontally. In the case of path due to moisture penetrating between the a phantom transposition, it is necessary to two parts of the insulator. arrange four insulators'one above the other. This object, as well as other objects of the This result has heretofore been accomplished invention, is accomplished by means of the v by mounting brackets upon the crossarms arrangements shown inthe drawing, in which may carry one or more insulators above which Figure 1 illustrates how a side circuit a given i lat on th emssarm, transposition is made in accordance with the The provision f the bracket and ther present invention; Fig. 2 illustrates how a hardware necessary to accomplish this result phantmn transposition is made in accord involves a considerable amount of expense, ance with the present invention; Fig.3 illusrender ng 1t desirable to; have available for trates in detail the two parts of the insulator use at transposition points an insulator cap of the present invention mounted in assemable of carrying at least two wires, one above bled relation upon a supporting pin, while of transposing a pairof Wires without th en through the two respective parts of the use of any brackets whatever, and in the case In ul torv p of a phantom transposition, a single bracket R f r ing to Flg- 1, poles A, B and C are carrying a single double insulator would be Pr vided With OI'OSSaI'mS X, Y and Z, respecall that would be required. When this is contively, and each crossarm carries a' pair of intrasted with the complicated form of bracket sulators upon which the line wire conductors capable of carrying three insulators, which 1 and 2 may be mountedjlnefl'ecting a transmust' be used for the ordinary phantom position, the problem is to cross the conductors transpositions, it is readily seen that a double- 1 and 2 between the poles A and C. The crossinsulator will effect a considerable saving. ing' is effected at the pole B by.means of a 40 Heretofore double insulators have been double insulator such as is illustrated at ,11, proposed made up of two units, one mounted capable of carrying two wires, this double upon the pin above the other, each unit servinsulator taking the place of the two ining to carry an individual wire. Such strucsulators and bracket customarily used in the tures have, however, not been practical betransposition arrangementsof the prior art.

' cause it has been impossible to provide a The transposition may be effected by conthe other. Such an insulator would permit Figs. 4 and 5 illustrate separate sections taknecting the conductor 19s it comes from the pole A to the upper part of the insulator .11

and the conductor 2 to the lower part of the insulator 11. The conductors are then given 5 another quarter-twist as they pass from the insulator 11 to the two insulators at pole C. If it is desired to make a phanton transposition, it will be necessary to provide a bracket to carry three single insulators above .the insulator on the crossarm at the pole B, if no double insulators are available. Fig. 2 shows, however, how relatively simple it is to effect a phantom transposition if double insulators are used.- Here a bracket is provided which carries a double insulator 11 above the double "insulator 11, mounted directly upon the crossarm of the pole B. The

' side circuit conductors 1 and 2 may be given a quarter-twist with respect to each other by connecting them to the upperand lower mounting grooves of the double insulator l1. Likewise,'side circuit conductors 3 and 4 may be given a quarter twist with respect to each other by connecting them to the upper and lower mounting grooves of'the double insulator 11. At the same time, due to the fact that the insulator 11' is above the insulator 11, the pair 12 is given a quarter-twist with respect to the pair 34. The conductors 1 so and 2 are given a further quarter-twist with respect to each other by connecting them to the fourth and thirdinsulators, respectively, of the pole C. Likewise, the conductors 3 and 4 are given an additional quarter-twist with respect to each other by connecting them to the second and first insulators, respectively, of the pole 0. Since the pair 12 is connected to the third and fourth insulators at the pole C and the pair 34 to the first and second insulators at the pole C, it is evident that the pairs have been given a further quarter-twist with respect to each other, Consequently, not only are the conductors of each pair completely transposed but the pairs themselves are transposed. All of this is accomplished by using a bracket capable of carrying one insulator.

The form of the double insulator of the present invention is illustrated in assembled form in Fig. 3, the separate parts of the insulator being shown in detail in Figs. 4 and 5. As will be seen, the insulator comprises two main bodies M and N, the part M being provided with a groove 21 and the part N with a groove 22. The two conductors to be supported by the insulator are led in these grooves and secured by means of tie-wires in a manner well understood in the art. Above the groove 21 a flange 23 projects outwardly to complete the groove for retaining the upper wire n position. 'Just below the groove 21 of the part M an umbrella or mushroomlike flange 24 extends outwardly and downwardly, this flange being formed on its under 65 side with aplurality of deep corrugations 25--26 to form an effective dry path between theconductor attached to the groove 22 of the part N. Below the groove 22 a skirt 27 projects downwardly, the skirt being corrugated on its inner side as shown at 28 to form an efi'ective dry path between the conductor sulator may rest, and the upper part of the 2 pin is tapered as shown at 34, the tapered part being screw-threaded near its upper end so that'the part N of the insulator may be screwed upon the end of the pin wlth the part N resting upon the shoulder 33. When so mounted, the upper part M of the 1nsulator clamps down upon the part N and holds it firmly in position. As the tapered part 34 of the pin is of smaller diameter than the tapered opening 31 of the part N of the insulator, a small air-space will be provided between the material of the insulator and the pin when the parts of the insulator are mounted upon the pin in the manner above described.

It is evident that .when the two parts are mounted upon the pin, as just stated, their contiguous parts will hear u on each other. In order to prevent the possibility of moisture finding its way between the two parts at their bearing surfaces, these surfaces are specially formedr As will be clearly seen in Fig.3, the upper surface of the part N is stepped as shown at 36 and 37 to form a shoulder. This shoulder is just above an outwardly extending flange 38 of the same general form as the flange 23 already described in connection with the part M. The part M, on the other hand, is likewise stepped as shown at 38 and 39 to form a mating shoulder, the step 39 being, in efiect, a small flange extending downwardly from the under side of the part M. When the two parts are assembled upon the' pin as shown in Fi 4 the flange 39 rests upon the step 37, and, as the upper part of the insulator is screwed down, rocks the lower part N of the insulator upon the flange 33 of the pin 29 so that the upper part of the insulator becomes firmly seated upon the lower part. The pin 32 is of slightly less length than the total depth of the opening 31 in the part N and the screw-threaded opening 32 in the part M so that when the part M is screwed down as far as it will go a slight air-space 35 remains above the end of the pin 29. This prevents the upper part of the insulator from being screwed against the end of the pin 29 thereby leaving a small gap sulator. Furthermore,.the shoulder 38 extends outwardly under the lip betweenthe 'two corrugations 25 and 26, and the outer part of the flange of the mlishroom-like flange 24 extends downwardly around the edge of the flange 28. The result is that a tortuous path is provided from the lower edge of the flange 24, the junction point of the two parts of the insulator rendering it very diflicult for moisture to be driven to the junction point by the action of rain and wind; Practicall'y the only way in which moisture can collect in this irregular passage is by condensation.

If any moisture should collect or be driven into the passage and through the joint formed by the parts 37 and 39, such moisture would have to be driven through the joint with such force as to rise up over the shoulder 36. If this should happen, the two adj a? cent parts of the elements-M and N are so shaped that an annular space 40 willbe formed about the pin 34 to trap the moisture without permitting it to touch the pin. The 11? oisture thustrapped will then run down the interior surface 31 of the insulator (there being an. annular space between the tapered part 34 and said inner surface 31), the: moisture then passing out over the flange 33 of the pin. The flange 33 does not form a tight joint with the shoulder 30 of the element N so that the moisture can escape' As has already' been pointed out, an airspace is formed around thetapered portion '34: of the pin in the neighborhood of the con ductor carrying groove' 22. This air-space is an important feature of the present invention as it serves to decrease the attenuation due to leakage. As is now well understood, the attenuation due to the use of insulators is to a large extent made up by leakage losses due to the material of'the insulator. These leakage losses are in the nature of a hystere esisloss which is a function of the capacity of the-insulator acting as a condenser. The

condenser action is due to the line conductor and thewet surface (if any) i on the outside of the insulator forming one plate, the other plate being formed by the supportmg pm which may be, and frequently is, metallic, and even if not metallic, becomes conductive when wet. The body of the insulator, of course, constitutes the dielectric. I

'. Now, if the dielectricmaterial of' which very the insulator is composed has a small loss anglc, the attenuation will be reduced.- This the insulator as a condenser, we may represent its effect as that'of a conductance shuntcd about a capacity, the conductance being the factor which produces:v the dielectricwloss.

' will be clear from the fact that if we consider If this conductance component which proiluces the dielectric loss is 'zero, the only effect on transmission through the condenser is to produce a change in phase without loss. of y In other words, only a wattless ourenergy. rent ows through the insulator in such case.

Consequently, if the niaterial of the insulator be a material having a low loss angle, and consequently a low conductance component, the leakage loss willbe greatly reduced. It has been found that the commer cial form of glass known as pyrex B has a very low loss angle and for this reason it is preferred to construct the insulator of this material. The effectiveness of the structure to reduce losses is very materially increased, as

already stated,-by means of .the air-space between the tapered portion of the pin and the inner wall of theinsulator adjacent to the groove 22. This is for the reason that the air-space forms part of the dielectric, and air, as a dielectric, has a loss angle very. closely approachin zero. Consequently, the combined'eflect 0 loss angle between the groove 22 and the pin, to ether with a layer of air, results in a ni aterial decrease in the leakage loss of the insulator 'so far as the conductor attached to the. grodve 22 is concerned. I

Another factor producing an attenuation loss is the direct current leakage'due to moisture extending from the conductor in the groove 22' over the skirt to, the pin 29. By providing the corrugations 28 on the inside of the skirt, a part of this path'will be practically dry so that the leakage loss due to this factor will be toa considerable extent eliminated. In a similar manner, the direct current leakage due to moisture will be reduced so far as the conductor applied to the groove 21 is concerned, by means of the corrugations 25 and 26 on the under side of the wide flange 24. This flange also extends out .a considerable distance for the purpose of maintaining the upper part of the outer surface of the skirt 27 dry just below the groove 22. This results in a substantialelemination of direct current leakage except when a driving rain occurs.

' In mounting the insulator upon the pin,

as I

.7 having a glass of low the flange 33'of the pin, which coacts with the insulator as shown at 35. When the insulator is wet, the entire upper surface of the flange 23 becomes conductive, and with the conductor in the groove 21, comprises one plate of a in the attenuation under these conditions.

The fact that a small air-gap 35 is included between the pin and the upper surface of the insulator results in decreasing the dielectric hysteresis due to the flux passing from the upper surface of the insulator to the upper surface of the pin. This again is for the reason that air has a very low loss angle.

It will be obvious that the general principles herein disclosed may be embodied in many other organizations widely different from those illustrated, without departing from the spirit of the invention as defined in the appended claims. I

What is claimed is;

1. An insulator. for transmission conductors comprising two bodies of dielectric ma terial, a groove in each of said bodies for the .attachment of transmission conductors, the

adjacent surfaces of said bodies being correspbndingly stepped so as to mate with each other and form a substantially water-tight joint when the two bodies are mounted one upon the other,'a downwardly and outwardly extending flange on the upper body below the groove thereof, convolutions arranged in echelon formation on the under side of said flange, and an outwardly extending flange on the lower body above the groove formed therein so related to the convolutions on said *first mentioned flange as to form a tortuous passage to prevent moisture from being driven into the joint. v v

2. An insulator for transmission conductors comprising two bodies of dielectric material of a generally cylindrical form each having a groove in its outer surface for the accommodation of electrical conductors, stepped surfaces upon the. adjacent ends of said bodies to forma watertight joint, a

flanged insulator pin, an interiorly screwthreaded opening for the upper body whereby it may be mounted on said flanged insulator pin, a corresponding opening through the lower body, said latter opening being of somewhat larger diameter than the insulator pin to form an air-space between the insulator and the pin, and a shoulder on the lower body to coact with the flange upon the insulator pin so that when the upper body is screwed upon the pin the lower body may be rocked upon the flange of the pin so that the adjacent surfaces of the two bodies will come into intimate contact there- .accommodation of electrical by preventing moisture from entering at the unction point. j

3. An insulator fortransmission conductors comprising two bodies of dielectric material ofa generally cylindrical form each having a groove in its outer surface for the conductors, stepped surfaces upon the adjacent ends of said bodies to form a water-tight joint, a flanged insulator pin, an interior-1y screwthreaded opening for the upper body wherebyit may be mounted on said flanged insulator pin, a corresponding opening through the lower body, said latter opening being of somewhat larger diameter than the insulator pin to form an air-space between the insulator and the pin, a shoulder on the lower body to coact with the flange upon the insulator pin so that when the upperbody is screwed upon the pin the lower body may be rocked upon the flange of the pin so .that'the adjacent surfaces of the two bodies will come into intimate contact thereby preventing moisture from the entering at the junction point, and an outwardly and downwardly extending flange upon the upper body to prevent mois ture from penetrating to the joint between i the two bodies 4. An insulator for transmission conductors comprising two bodies of dielectric material ofa generally'cylindrical formeach hav ing a groove in its outer surface for the accommodation of electrical conductors stepped surfaces upon the adjacent ends of said bodies to form a water-tight joint, a flanged insulator in, an :interiorlyv screwthreaded opening or the upper body.whereby it may be mounted on said'flanged insulator pin, a corresponding opening through the lower body said latter opening being of somewhat larger diameter than theinsulator pinto form an air-space between the insulator and the pin, a shoulder on the lower body to coact with the flange upon the insulator pin so that when the upper body is screwed upon'the pin the lower body may be rocked upon the flange of the pin so that the adjacent surfaces on the two bodies will come into intimate contact thereby preventing moisture from entering at the junction point, and a downwardly and outwardly extending flange upon the upper body, said flange having corrugations on its under surface to prevent moisture frompenetrating to the unction between the two bodies.

5. An insulator for transmission conductors comprising two bodies of dielectric material of a generally cylindrical form, an interiorly screw-threaded opening for the upper body whereby it may be mounted on a flanged insulator pin, a corresponding opening through the lower body, said latter opening being of somewhat larger diameter than the insulator pin-to form an air-space between the insulator and the pin, a shoulder on the lower groove inthe lower bo y cooperating with the lips of the corrugations upon said first penetrating. to the'joint. "f I 6. An insulator for transmission conduc- Hmentioned flange to-preventmoisture from tors comprising two generally cylindrical I bodies each having 'a' groove in its outer sur face forthe accommodation of electrical conductors, stepped surfaces upon the adjacent -.ends of said bodies to form a water-tight joint, a supporting pin u on which said bodies may be-mounted, a ange upon said supporting pin, an interior opening in said 5 lower body of somewhat larger diameter than the supporting pin, and ,a shoulder upon said lower body whereb thei'said body will be supported by the aiigeof. the supporting pin withan air-space between the'body'and the pin, afscrew-threaded: pening infthe upper body whereby/it may be screwed upon a threaded portion of the in, the length of the .pin above its shoulder eing somewhat less than the total length of the interior openings in said bodies whereby when the upper body 'is screwed down upon the pin until its lower surface comes in contact with the upper surface of the lower body the lower body will be rocked upon the flange of the pin to bring I the two adjacent surfaces into intimate contact to prevent water from, entering the joint, the arts when so mounted leaving an air-space etween the upper part of the pin and the top wall of thesupper body.-

,7; An insulator for transmission conductors comprising two generally cylindrical bodies each having a roove in its outer surface for the accommo ation of electrical conductors, a supporting pin upon which said bodies may be mounted, a flange upon said supporting pin, an interior opening in said a lower body of somewhat larger diameter than the supporting pin, a shoulder upon said lower body whereb the said body will be supported by the ange of the supporting pin with an air-space between the body and the in, a screw-threaded opening in the upper ody whereby it may be screwed upon a threaded portion of the pin, the length of the pin above its shoulder being somewhat less in said bodies whereby when the upper body is screwed down upon the pin until its lower surface comes in contact with the upper sur- 66 face of the lower body the lower body will be an outwardly extendin flange above the 1 than the total length of the interior openings rocked upon the flange of the pin to bring the two adjacent surfaces into intimate contact to prevent waterfrom entering the joint, the parts when somounted leaving an air-space between the upperpart of the pin andthe top 70 wall'of. the upper body, and flanges below the groove on the upper body and above the grooveon the lower body,,said flanges being shaped to-form a tortuous passage to prevent moisture from being driven to the joint.

'8. An insulator tor transmisslon conductors comprising two bodies of dielectric material of generally cylindrical form, each having a groove in its outer surface for the accommodation of electrical conductors, a support so ing pin upon which the two bodies may be mounted one upon the other, said supporting pin having a flange thereon and a screwthreaded end, an opening through the lower body somewhat larger in diameter than the 5 pin, and said body having a shoulder whereby it may rest upon the flange of the supporting pin without coming into contact with the pin above the flange, an interiorly screw-threaded opening in the upper body whereb it may be mbunted upon the screw-threade end of the supporting '.pin and stepped surfaces 7 upon the adjacent elids of said bodies wherebywhen the'lower body is seated. upon the flange ofthe supporting pin and the upper body is screwed upon the pin the lower body will be rocked upon the flange to bring said step ed surfaces into intimate contact to form a su stantially water-tight joint, the length ofthe pin above the flange being somewhat shorter than the total length of the openings in the two bodies so that when mounted upon the pin the upper body may be screwed tighty down upon the lower one.

, 9. An" insulator for transmission conduc- 05 tors comprising two bodies of dielectric material of general cylindrical form, each having a groove'in its outer surface for the accommodation of electrical conductors, a sup-.

orting pin upon which the two' bodies may no he mounted one upon the other, said supporting pin having a flange thereon anda screwthreaded end, an opening throughthe lower body somewhat larger in diameterthan the pin, and said body having ashoulder whereby I it may rest upon the flange of the supporting pin'without coming into contact with the pin above the flange, an interiorly screw-threaded opening in the upper body whereby it may be mounted upon the screw-threaded end of the supportingpin, stepped surfaces upon the adjacent ends of said body whereby when the lower body is seated upon. the flange of the supporting pin and the upper body is screwed upon the pin the lower body will berocked upon the flange to bring said stepped surfaces into intimate contact to form a substantially water-tight joint, the length of the pin above the flange being somewhat shorter than the total length of the openings in the two bodies so that when mounted upon the pin the upper body may be screwed tightly down upon the lower one, and flanges one upon the upper body below the groove thereof and 5 one upon the lower body above the groove thereof, said flanges being so shaped and related to each other as to form a, tortuous passage to prevent moisture from penetrating to the joint between the two bodies.

I In testimony whereof, we have signed our names to this specification this? th day 011 December 1925. 7 CHESTER s. GORDON.

JAMESJT. LOWE. 15

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