US1626777A

US1626777A - High-potential conductor

Info

Publication number: US1626777A
Application number: US722440A
Authority: US
Inventors: Arthur O Austin
Original assignee: Ohio Brass Co
Current assignee: Ohio Brass Co
Priority date: 1924-06-26
Filing date: 1924-06-26
Publication date: 1927-05-03
Anticipated expiration: 1944-05-03

Description

May 3,-1927.

A. o. AUSTIN" HIGH POTENTIAL CONDUCTOR Filed June 26. 1924 2 sheets-sheet 2 f INVENTOR BY L@ ATTORNEYS vso tion.

Patented May .3, 1927.

UNITED STATES PATENT., OFFICEQ Ammon o; AUSTIN, or eliminaron, omo, Assrenon, nr Mestre AssieNMEN'rs, 'ro 'ran 01110 nnAss comenzar, or MANsrrnLn; omo, a ooaroaerron' or new ran- SEY.

l HIGH-remnant connno'ron.

\. i Application led ,Tune 26, '1924. Serial No. 722,442@

This invention relates to conductors for reducing corona losses at high voltages and has lor its olneet the vprovision of conductors which' shall he mechanically and electricallyV jeliicient and 'l in which the losses due to corona will he reduced. l

The invention is exemplified in the combination and arrangement of parts shown in the accompanying drawings in the following specification and it is more particularly pointed out in .the appended claims.

ln the drawings- Fig: 1 is an elevation of a'portion of av conductor having onefemhodiment of the present invention applied thereon.

Fig-2 is a transverse section .of doctor shown in Fig. 1.

Figs. 3 and 4 are views and 2 `showing 'another form of tion. l

Figs. fand are views similar to Figs. 1 and 2 showing another form of theiinvention.

Figs. 7 and 8 are views similar to Flgs. 1 and 2 showing yanother form olrtheinvention.

Figs. 9 and 10 are views similar' to Figs. 1

the consimilar to Figs. l

the invenand' 2 showing another jformof the invention. f

Figs. 11 and, 12 are viewssirnilarA to Figs. 1 and 2 showing another form of the invention. y f

Figs. 13 and 14 are views similar to Figs. 1 and 2 showing another form ofthe invention.

' Figs. ,15 and 16 are views similar to Figs. 1 and 2 showing another form of' the invention.

Figs. 17

and 18 are views similar to Figs. 1 and 2 showing another vform of the inven- Intransmission at high voltages the discharge into the air or corona loss is an important economic factor. Since the amount of power which can he transmitted over a conductor with a given percentage loss increases as the square of the voltage, it is highly important 'that a high voltage be used in order to reduce the size of the conductor and lower the costpoi the transmis-V sion line. For a given amount of power, by increasing voltage, ,the size of the conductor canbe decreased with the same percentage and described v larger streams; hence,

of loss. It the voltage is high, however, the smallsize conductor may vdischargevinto the iur and the increased loss odset economic gains in reducing the size of the conductor llVhere very high voltages are used, smooth conductors may operate with corona loss. Under storm conditions, ever, the smooth conductor may have a very small rough lower edge formed hy the drip water running oil of same.. With a smooth conductor, this water tends to run oli in much the losses may really he greater and. the danger oi' arcing" to ground may he materially increased, as against a conductor which has a fairly uniform roughness which will break up the drip water into small quantities. l

The conductors shown in Figs. 1, 2, 3, e, 13, 14e, 15, .and 16 accomplish this result by the main corona pressing strands, whereas the attaching or binding members hold 'l the vcorona pressing stran to the main condpctor tend to accomplish the same result in Figs. 5,6, 7, 8, 9, 10, 11, and l2. A small conductor which will brealr' up the drip water may have lower losses and he less likely to permit an are to, form from conductor to ground than a very large smooth conductor where the latter permits a concentration of the drip water at fewer points. l Not only does `the concentration of the drip water from a larger conductor tend to cause discharge or increase the losses but the larger projected area of the large conductor tends to increase the amount of' drip Water and the length of the stream falling from the conductor. With a larger radius of curvature, there is also, less tendency to `break up the stream of Adrip water.

properties might be used to advantage.

large v howv .If thesize of the conductor, however, 1s

too small, the losses will be high and the compounds formed by the discharge will ten to destroy the conductor.

n addition to the installations where the amount of power-transmitted 'will hardly warrant a large conductor, there are installations where the loss is likely to he very considerable from 'corona discharge, owing to the very highvoltage useda` This loss is greatly increased where the altitude is high or under storm conditions where the conductor is wet.

lu a. very large conductor, the brush discharge tends to startI abruptly at some point ou the voltage wave and may cease abruptly. 'lhis tends to set up oscillations which it would be desirable to eliminate. The corona discharge is due to aJ high electrostatic stress in the air. This stress may be reduced by increasingl the size ot the conductor or by substituting a material which has a higher dielectric vstrength than air. v

`Where the projected area oli'the conductor is large,.the amount. oi water intercepted during a rain may be considerable. Even though 'the-conductor is quite large, the

water falling ofi' the lower partof the conductor forms an exceedingly sharp edge and tends to increase the loss. 'This tends to oilset the benefit of the large diameter.

ln very largeconduetors there is also a tendency for the discharge to be less uniform than in the case of the small conductors; hence,`a discharge at any point on the large -conductor may be larger and project further into the air than in the case'of the small conductor. This is due to the fact that in the small conductor there is a mutual screening etteet owing to the numerous discharges which re-act upon each other, while in the large conductor the absence to a large extent oit `such screening action permits a streamer or discharge to aiect a larger electrostatic tield. This tends to ott'set the advantage of the large conductor and it is therefore highly advisable to prevent discharge from the larger size of conductor as well as the smaller size of conductor.

lf the entire conductor could be covered with an insulation which should have a greater strength than that of air, the desired result would be obtained. It would be prac,- tically impossible, however, to maintain insulation of this kind owing to the cost and aging of the same. A very material et'ect, however, may be obtained by providing a few conductors which* project beyond the outer layer ot the main conductor and covering the projecting conductors with insulation such as insulating enamel, rubber,

guttapercha or other suitable material. `In

order to obtain a material benefit it is not necessary that the insulation be continuous on the project-ing conductor constituting the control or corona suppressing strands.

ln general, the covering of a conducting surface with insulation with greater dielectric strength than that of air permits the projection of this conductor further into the `electrical field, in order to provide a` screening action for suppressing discharges from electrodes orcondncting surfacesI in this vicinity, the inner portion of the insulated control being connected electrically to the body which it`is desired to protect.

Figs. l and 2 showone method ol' producing thedcsired result. The conductor is composed otl a main conductor l similar to that generally used for transmission work, the one shown in the drawing comprising a plurality of strands. strand 2 having a covering 3 oi dielectric material is wound around this conductor l so as to project outwardly from the surface. The distance between turns ofthe winding 2 may vary in accordance with the result desired. ln place of a single strand, two or more strands may be used. These strands may be wound in the same direction and may contorni to the lay of the cable, or, the individual strands may be wound in opposite directions to each other. Where a tewvstrands only are used twisted around the conductor, these strands may be installed by proper equipment even after a cable-is in position. The corona suppressing strand 2 may have little or no insulation on the inner surface 4where it comes in contact with the main conductor. It matters littlev whether electrical contact is established at the time that the strand is puton or not as insulation will be broken down by the charging current and this will effect goed contact. If a conducting strand is used, a' drop in potential along the main conductor will also insure contact between the coro of the protecting strands and the main conductor. It is usually not necessary to make a detinite'metallic Contact between the conductor and the core of the corona suppressing strands for the reasons stated above, although this may be accomplished in several different ways. It thereis no contact at the time of installation, vibration will tend to maintain a contact surface, particularly it the corona suppressing strands are'wound loosely about the main conductor.`

Figs. 3 and t'show the several corona sup pressing strands or elements, the number 4 designating the cor'o a suppressing strands and 5 the strands of the main conductor. kThese strands may be wound with the same lay as the main conductor or in opposite directions. If wound in an opposite direction, it is usually advisable to apply varnish or material which will cause the strands to maintain their relative position unless they are close together. lVhen wound in a lay corresponding will tend to stay in proper position, although it may be advisable to wrap the conductor with a protecting material until time ot installation.

:Figs 5 and 6 show a similar construction to that in the other tigures with the excepto that inthe cable they4 diictor 111 must be established occasionally.

lll)

tion that the corona suppressing 'strands 6 may be supported parallel with the axis ot the main conductor or spiraled around it. The corona suppressing strands 6 are held to the main conductor strand 7 either wholly orpartially by a small wire orbinding strap '8 wound around saine.

This binding member -should preferably be of insulating inaterial7 although it may he of metal in .the form ot' a bare wire or member covered with insulation as in the case of the corona' suppressing strands-6.' Any 4equivalent .construction such as rings oi stainpings may he used for the purpose. If. the corona suppressing strands have a high degree o'fiiisiilation they may be located at some distance from the conductoras in ll1 igures 7 and 8. vln Figures 7 and 8 the construction is somewhat similar to that inl Figures 5 and ,6

except that a single corona suppressing,

strand 9 is used hung-below the conductor. This strand may be spaced -from the conductor and attached to the same mechanically only at yfrequent intervals. This strandy will tend to minimize the discharge trom- 'drip Water.- In this case 9 is the corona'suppressingstrand, 10is the main conductor and 11 the mechanical connecting means between the corona suppressing strand and the main conductor. y

In Figs. 9 and 1.0 two protecting strands 12 are shown so that the drip water may fall directly 'from the main conductor and not from the corona suppressing strands. With this arrangement, less insulation is required on the corona suppressingv .strands as the drip Water tends to leave the main'conductor strands 13 directly rather than from the corona suppression strands 12.` The corona suppressing strands`12 are preferable spaced 'from the main conductor strands 11 by a small strap or holding means 14.

Figs. 11 and 12 show one method ol' attaching to the main conductor which will tend to hold the corona suppressing strands 15 at a distance from the main conductor. The attaching means 16 may be kin the torni ot Water resisting cord or wire or metallic members may also be used, as they are needed only at intervals suliicient to obtain proper spacinf. Where the attaching member 16 is a poor conductor, electrical contact between the core. of the suppressing con- This maybe done by several turns of Wire 17 or a little metal ring placed about the conductor which Will come in contact with the inner edge of the corona suppressing` strands 15 and establishcontact.

Where a considerable amount oi protection is desired or very quiet operation is desired, as around bus structures, a construction shown in Figs. 13 and 14 may be used to advantage. In this case the corona suppressing element 18 is made up in the form of a helix having a. milch larger diameter than the main conductor 19. The member 18 may be 'attached to the main. conductor 19 by another wrapping 2O so as to lreepthe turns of the helix iii'pi'oper position.

The strands of the corona suppressingele- A ments may be made in a number of diil'erent 'ways without changingtlie principle ot the invention. One method is to app y a layer ol' material which may be impregnated with a. varnish or insulating material to increase its dielectric strengthor to provide Water protection, such as cotton Wrapping impregnated with linsced oil or an insulating varnish. Even though there' may be some deterioration in time, it is a comparatively easy matter to coat the outer-portions of the Y ywill strike from the conductor to ground.

This tends to reduce the danger of grounds on the system. l l

pFigs. 15 and'lG show the conductor made up having corona suppressing strands 22 having the same lay as the main conductor strands 21. Figs. 17 and 18 show a conductor having the -corona suppressing strands 24 meshed with the main'conductorvstrands 23. This arrangement tends to prevent the displacement ot the coronasuppressing strands.

'l claim:

1. In an electrical transmission line for high potentials a current carrying conductor having 'portions disposed along the lengthythereo and projecting beyond the main contour of said conductor, said projecting portions loeing electrically connected with the main body of said conductor and covered with dielectric material to reduce Acorona loss in said conductor.

2. 1n an electrical transmission line `for high potentials a current carrying con ductor having a plurality of periplierally protecting longitudinally extending ribs,

said ribs having electrical connection with `'said conductor and having the outer portion thereof projecting beyond the main contourr on the conductor hut in electrical connection thereivith, the outer portion of the projecting `tend to cut down the' coronalosses which iso strand being covered with dielectric material. 4. In high lpotential transmission lines, a bare. conductor and-a strand of dielectrically covered material wound upon said.

bare conductor said strand having electrical connection Withsaid conductor.

5. In high potential transmission lines, a bare current carrying conductor and a plurality of strands of dielectrically covered conductor material Wound upon and in electrical connection with said bare conductor and arranged in spaced relation about the v.periphery thereof.

, 6. In high potential transmission lines, a conductor comprising a plurality of strands :all in electrical contact,'oue of said strands having its Vouter portion arranged to project beyond the contour of the conductor i ARTHUR o. AUSTIN.