US1694415A - Insulator - Google Patents

Description

5 N 2 @Rw Lv. Gwlm KNvu S I d C l F Dec 1l, 1928.

lllllllllll l# INVENTOR 5- G10/@Z010 Y B W ATTORNEY 45 attenuation of the circuit.

vPatented Dee 11, 1928. l y

UNITED STATES PATENT OFFICE.

CHESTER S. GORDON, OF NEW YOBX, N. Y., ASSIGNOR TO AMERICAN TELEPHONEl ANO TELEGRAPE COMPANY, A CORPORATION F NEW YORK.

- INSULA'roB.

Application mea my 1,

This invention relates to improvements in y insulators and more particularly to a" construction of insulator adapted to stabilize the leakage loss under different weather conditions.

Withthe development of methods of transmitting telephonie and telegraphic signals b means of carrier currents propagated allong open wire lines, new transmission problems have been introduced. Owing to thev fact that the carrier currents employed are relatively high in frquenc as compared with the voice currents or orse currents utilized in the ordinary methods of communication ityhas been found that the attenuation is ve markedly increased, vso much so, in fact, t at repeaters for amplifying the transmitted currents must be separated by much shorter distances, thereb adding to the expense of then lant outsi e the terminal stations at whic the carrier apparatus is applied. y v

A very material part of this attenuation is due to leakage loss throu h the insulators which are customarily emp oyed upon o en wire lines, and this loss varies throug a very wide range under different weather conditions. The insulator acts like a condenser, `the glass of the insulator constituting the diso electric, the 'line wire and tie wire on the outside of the insulator com rising one plate, and the wooden pin upon w ich the insulator is supported com risin theother plate. The-4 condenser thus orme introduces a leakage loss due to so-called dielectric hysteresis and this loss varies with theoapacity of the condenser.'

In dry weather, the outer plate of the condenser, that is, the portion of the'line wire ad- 40 jacent the insulator and its. associated tie wire, constitutes a plate of relatively small area. so that the capacity is relatively small and hence the leakagel loss, even at carrier frequencies, is small as compared with the total During wet weather, however, the entire outer surace-of the insulator becomes wet, with the result that the conductive area external to the insulator is very much increased. As a result, the

capacity, and consequently the leakage loss,

is very much increased. During the extremes of wet and dry weather theattenuation of the s stem varies throu h a wide range due to t 's cause alone, an this necessitates u the provision of special regulating apparatus 1925. Serial No. 40,894.

for maintaining the transmission equivalent of the circuit constant under all weather conditions.

In order to avoid the expense of the regulating arrangements it becomes necessary to devise some method for stabilizing the capaclty of the insulator, and hence its dielectric loss, at some constant Value. In accordance with the present invention it is proposed to stabilize the capacity of the insulator at substantially its dry weather value, thereby not only eliminating the necessity for transmission-regulating apparatus but also ref ducing the number of repeaters requisite, since 1t will only be necessary to provide a suiicient number of repeaters to take care of the smaller losses experienced in dry weather.

The invention ma now be more fully understood from the fo lowing detailed description when read in connection with the accom- "5 panylng drawing, in which Figures l and 2 illustrate two embodiments of the invention.

In order to stabilize the loss-of an insulator at substantially its dry Weather condition itis necessary to prevent moisture vfrom coming into contact with any surfaces of the insulator which are contiguous to the line conductor and tie wire. This may be conveniently accomplished by inverting the insulator. In the ordinary pole line construction supporting pins extend upwardly from the cross-arms and the insulators are mounted on the su porting pins above the cross-arms. Inaccordlance with the present invention the insulator is so designed that the supporting pins may extend downwardly from the crossarms and the insulators are supported on the pins below the cross-arms.

An insulator adapted to be'used in this manner is shown in Fig. 1, in which A is a 'bod of dielectric material having an interior y screw-threaded opening 10 extending down into the body from the top. This openin is adapted to permit the dielectric bod to screwed upon a supporting pin exten ing downwardly from a cross-arm. At the lower end of the body a shoulder 11 is provided upon which the line conductor and tie wire may be secured.' In orderto prevent moisture due to rain or other form of precipitation from rcoming into contact with the shoulder -11 or the insulator surface either immediately above or immediately below said shoulder, the dielectric body A is provided with an external pet-ticoat '12 extending out- 110 wardly and downwardly as shown, so that the lower ed e of the etticoat is only ,slightly above an some litt e distance outward from the shoulder 11. In order to lengthen the.

dry path above the shoulder 11 to still further insure thattliere'will be no conductive connection between the line conductor and tie wire and the upier surface of the insulator 10 (which is infin uctive relation to the supporting pin an additional petticoat 13 may be vprovide between thevouter petticoat 12 and the main body A.

It will be clear that a constructionsuch as that above described will prevent the surface of the insulator in the neighborhoodof `the line conductor and tie wire from becoming wet and hence there will be no substantial enlargement of the conductive area in the nei hbor hood ofthe line conductor and tie wire uring vwet weather. Accordingly', the alternatin current leakage of the insulator is stabilire at a condition correspondin substantially to dry weather condition.V urthermore, the direct current leaka is stabilized at the dry weather condition the provision 'of the long vdry-paths due to the under petticoats near the top 'of the insulator. vBy stabilizing the lo due to the insulator at o r near the' dry lweather Vcondition vthe number` of Vrepeaters necessary will be somewhat reduced, but what is moreimportant, 'it is-no lon ger necessary' to 'provideequipment for maintaining the transf mission constant for thetransmi'ssion will not materiell vary between extremes of wet 4and dry weat er. l l

A slightl modified arrangement is illus-Y trated in Fig. 2. In this case the shoulder to support the line 'conductoraY and.l tie wire is formed by an auxiliaryfcap-likememberB whose internal bore is screw-.threadedso that it may bescrewed uponc'orresponding screw, threads 15 .upon the main. dielectricbo'dy C. The shoulder 11 is'then .formed by the'upper edge of the member B. This-construction has theadvantage that itis muchfs'impler to mold the dielectric material-in two.parts', as shown in Figt', than it is tomo'ld the' insulatorv as an integral whole in the? form shown ,in 1.

Electrically, the arrangements of Figs. 1 and 2 are substantiallyy the same.l

It will be obvious that the general principles herein disclosed may be embodied in many other organizations widely different from thosev illustrated without de arting from the spirit of the invention as dened in the following claims.

What is claimed is:

1. An insulator comprising va body of dielectric material having an internal screw threaded opening downwardly extending from the top into which aldownwardly extending supporting pin may be screwed, a caplike'member Aof dielectric material ar vto be secured to the lower end of said bod to `form' a shoulder above which the line con uctor and tie wire maybe secured, and a memher 'extendin outwardly and downwardly from said bo y to prevent moisture from being deposited 4on said shoulder, the shell of said body between.` said: shoulder yand said member being of substantially uniform thickness.

2. Aninsulator'comprising a body of dielectric material :having an internal lscrew threaded `opening' downwardly a extending from the ltop into lwhich *a downwardly extending supporting pin' may be screwed, a cap- ;like member of dielectric material arran A.to-be secured to the lower end of said'bod to Vf orrn ashoulder above which the line con uctor and tie wire may be secured, a member exft'en'ding outwardly and downwardly from said 'bodyto'prevent moisture from be' de ited on saidshoulder, the shell ,oflagid bdsy between shoulder and said petticoatbeinglf substantially uniform thickness, and an.; 'auxiliary petticoat interposed between aaidoutwafrdly and-'downwardly lexten 'memberyand` said hodytof increase the' lerclg I' 'if the dr :path-from theglower'margin of saildl-memnA I h u v -,testiinony-wcreo', avengned'"4 in'v l'namef to 'this specification :this 25th iday 05% Jllleyilm.

orms'ri'ia s. nonnen;

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