CA1168696A - Three phase transmission line conductor phase array - Google Patents

Abstract

A B S T R A C T
Disclosed is a single-circuit three-phase overhead electric power transmission line which comprises in ge-neral three bundled phases having their torstors attached to metallic spacers adapted to define in a pla-ne perpendicular to the axis of the transmission line cross-sectional configurations of the bundled phases secured by insulators to transmission line towers whose structural members are disposed outside the space occu-pied by the bundled phases and air gaps therebetween.In the disclosed electric power transmission line the adja-cent bundled phases are spaced apart substantially egui-distantly over the entire length of their configurations, while the sub conductors of the bundled phases are arran-ged not eguidistantly, 80 that electric chargers of the subconductors are egual, the electric field thus produ-ced being approximately uniform in the entire extent of the interphase gaps and liable to electric breakdowns upon the occurence of overvoltages in the transmission line in excess of those permissible proceeding in stream-er form only.
The invention provides a wide scope of possible configurations of the bundled phases, ~uch as closed, open and combinations thereof.

Description

~86~

The present ~nvention ~s conce~ned ~ene~all~ wi-th single-circuit three-phase ove~head alternating-cur~ent transmisS~Qn lines for h~gh, extra-high and ultra-high voltages, and more speci~ically relates to a single-circuit three-phase overhead electric power transmission line of the bundl-ed-phase type.

Bundled-phase type electric power transmission lines are known to incorporate in each of the phases thereof a few single bare subconductors, generally steel-aluminium.
These subconductors in the cross-section of an electric power transmission line are interconnected by means of metallic spacers to form configurations of the bundled phases. The bundled phases are affixed by insulators to 1~ transmission line towers, such as suspension, dead and, angle, anchor and the like. Such electric power transmission lines of the bundled-phase type exhibit a lesser surge im-pedance as compared with transmission lines wherein each phase is represented only by a single conductor, and for this reason they feature an enhanced power transmission capacity, i.e. a surge-impedance loading.

Owing to an increase in the blocks of power being nowadays transmitted on transmission lines, ever growing .
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re~uiremen-ts are produced in regard to a stepup in the power transmi~sion capacities o~ the li~es, which are to be met while en~uring their adequa~e levels of economic e~ficiency.
One of the possi~le expedi~nts for achieving an in-crease in the power txansmis~ion capacity of bundled--phase type alternati~g current transmission lines s to enlar~e the number of subco~ductors in the b~dled phases.
However, an i~crsase i~ t~e number o~ subconductor~ ~ith a decrease in their diameter bri~gs about a reduction 1 the length of spans; whil~ a~ increase in the ~um~er of subconductors without a decrease in thair diameter has caused in prior art tran~mission ~ines a rap~dlg attenua~
ting incremen~ of the power transmissio~ capacity o~ the lines, which i~ not re~,~.onable ~rom the economic poi.nt of vi~w.
Known in ~he prior ar~ i~ a sîngle~circuit three--phase o~erhead electxic power,tran~mission line oP th~
bundled-pha~e typ0 which has an increased number of ~ub~
conductors as opposad *O similar con~antiona~ prlor art trans~ission lines (~lexandro~ G~., Er~lov S.V., ~isoch-kina ~.V., ~yskov Y.I.3 Redkov V.P.~ "On the exp~die.~c~
of constructing overhead alternating-current tr~nsmissio~
lines with an increased conduc-tor bu~d~ing radlus", "Electric Power Plant~'~ jour~al~ "Energy" P~blisher~?
Moscow, ~o~ 8, 197~, pp. 48 55). ~he ~oregoi~g power ~L6~36 -- 3 ~
trans~issio~ line comprises in combination subconductors attached to metallic spacers de~ining cross-sectional co~figurations of the bundled phases in a plane perpendi-cular to the a~is of ~he transmission line, tower assemb-lies and i~su~ators ~or securi~g the pha~es thereto~ The li~e under cOnsideration has the bundled-phaæe ~onfigura~t-ions design~d in the ~orm of egual-diameter sir~es sspa rated in a horizontal direction~ tower posts being dis-po~ed ther~betwee~
In each phase o~ s~ch a transmission linel as in the case o~ other co~ventiona~ prior art tran~mission ~ines oî the bundled-phase type, the ~number o:f sul:lco~ductors is the same and the~ are evenly spaced apart, i.e~ the bundled pitch is consta~t in each phase and uni~orm for all o~ the phases~ Howe~er~ t~e numbex o~ subconductor~
in each phase of the transmission line descri.bea herein above is enlargea in comparison with the ~u~ber of subco~-ductors in the phases o~ other conventional prior art transmiSsion lines, a~d namely, up to 9 instead o~ the regular 4-5 ~or 750~kV transmission lines and up to 12-13 instead of th~ regula~ 8 for 1150-~V tr~nsmission lines~
In con~ormity with this increa~e in th~ number o~ subi;
conductors in the phases are aL~o increas~d the radii rp o~ the circles support m g the subconductors o~ ea¢h phase, thi~ being doné to maintain the u~ual bu~dling pitch bet~een the ~ubconductors. In this ca~e the ~nter~

, 365~6 phase spac~n~ the ~ansmiss~an line described is the s~me ~s ~n conventional prior a~t txansmission lines, i.e.
17 to 20 meters for 750-kV transmission lines and 23 to 25 meters fox 1150-k~ transmission lines. The increased radii o the circles carrying the subconduc-tors of each phase, i.e. the ~ncreased phase bundling radii, have en-abled to reduce a surge impedance to 150 ohms and to raise thereby a surge-impedance loading of the 750-kV transmission lines from 2 up to 3.5 x 106 kW and that of the 1150-kV
transmission lines from 5 up to 9 x 106 kW, that is by 70-80%.

In the transmission lines in question the inter-subconductor spacing of all adjacent phases is not the same and varies from S to S+4 rp. This circumstance to-gether with the substantial interphase spacing and the pro-vision of grounded towers between the phases result in the non-uniformity of the electric field in all of the interphase gaps.
When exceeding permissible overvoltage values, such an electric field is exposed to electric disruption phenomena occuring between the phases in leader form which ` ischaracterised by formation in the interphase gap of an air passage where the electric discharge takes place.
In order to warrant the requisite degree of electric strength in these conditions the phases should be separated by a comparatively large distance. All this leads to an app~eciable increase in the overall dimensions and cost of the ~ 6~ 6 tower assemblies9 as wel~ as to increase in the width o~ a right-o~-way corridor, which is eco~omically objectio~able consideri~g that a gain in the surge-impedance loading is fairly insigni~icant.
Another possible expedie~t for stepping up the power tra~smission capacit~ of a transmission line is to i~crea se the ~umber of phases. ~hus, know~ in the prior ar~ i~
a six~phase electric power transmission line with a vol-tage rati~g o~ 462 kV ("Electra", No. 61, 1958 (Paris): ~0 O.B æ tbho~d, "Rou~d table on transmission of electricit~
into the beginning of the 21-s-t ce~ury" 7 ppo 32-35)~
~ach phase o~ this transmission line is bundled into four ~u~conductors uni~ormly disposed on metallic spaceræ
around a phase center. The pha~es o~ the transmissîon line are also disposed around a common center9 while the elements of tower aæsembli~s are b~ough-t outside the spa-ce occupied by the phases and air ~aps between them. ~he 3pacing be~w~en the a~es of adjacent phases amounts to 4~9 m, while that between the nearest co~ductors of adja-cant phases amoun-ts to 4.4 m. ~he electric ~radie~t in the interphase gap at the amplitude value o~ an operat-ing voltag~e amounts in this transmission line to 1.5 kV/cm.
In this prior art transm~ssion ~ine, as in the cas~
o~ the line described hereinabova9 the subconductors o~
all adjacent phaæes are spaced a~art at varying dist~nces , ~ ' , ~ 6 and for this reason the electric field between the phases is nonuniform.
The towers o~ the a~o~e transmi~sion line have com~
paratively small overall dimensions a~d its surge impe~
,Y /,~Gk~
dance loading is high and amounts to 6~ , However, the six-phase transmission line calls ~or use of tra~for-mers with connection circuits employed in rectif~ing techni-que, whioh adds considerably to the eomple~ity and cost o~
such a tran~mission line.
Another expedie~t also know~ in tho prior art for increa~ing tho power transmission capacity of an alternat-ing -current transmission line o~ the bundled-phase type consists in forming ~n appro~imatel~ uni~orm electric field in the interpha~e gaps~ ~uch an expedie.nt ls diæ-closed in U~SOPatent No. ~72499773 i~sued May 3, 1966, whose specification describe~ two -transmission lines.
One of them is a single-circuit single-phase o~er-head electric power transmis~ion line comprisi~g in com-bination two arrays of subconductors attached to metalllc spacer~, a series of portal-type suspension towers and insulators, among which the in~uLator~ securing the lowe~
array of subconductors to the bower are suspension string insulators and the insul~toræ ~ecuring the uppe~ array of subconduckb~s are post insulatorsO ~he a~ove prior art trarlsmission line ~eatures the subconductor arrays disposed s~mmetrically about a hori~ontal tran3~v~ræe member o~ the tower, due to which -the latter is :Located ~ ~6 ~ 6~ ~

inside the space occupied bg the i~te~phase air ~ap~ ~he ~umber of subconductor~ in each array iB the same and they are equidistantly spaced a~art~
In this particular sîng~e-phase electric power tra~s-missio~ line the presence o~ a tower m~mber i~ the intar-phase gap, as in the case o~ other prior art transmission lines having a similar arrangement of towers? leads to a decrease in the degree o~ uniformity manl~ested by the electric ~ield between the phase~ and makes it in~^spe~-sable to enlarge their spacing. All this restricts -the power transmission capacity o~ such a line which in itsel~
is sma~l, inasmuch as this line is o~ the si~gle-phase type. ~urthermore, the provision o~ post insulators in the above llne9 which posseso a relatiuel~ sma~l strength margin upo~ the action o~ lo~gitudinal forces arising i~ the subcondu¢tors, e~tails the necessity of de~r~asing the len~th o~ spa~s and, as a co~sequense, an increase în the number o~ towers a~d în the CoBt of the tran~mission line.
A single-circuit ~hrae-phase overhead electric power ~ransmls~ion line o~ the bu~dled-phase type disclosed in the ~oregoi~g U.S.Pate~t is mo~t close~y rela~ed in its tech~ical essence to the sub~ect o~ the present în-ventîon and ~herefore identified a~ prototypal. ~his prior art ele¢tric power transmi~sîo~ line comprise~ in combi-natîon a plurality OI subconductors attachad to metallic ' spacers de~ining cross-sectional configura~ions o~ bund led-phases in a plane perpendicular to the axis of -~he transmission line 9 a ser.ies of towers whose members ~ce disposed outside the space occupied by -the phases and air gaps therebetwee~, a~d insulators securing the phases of the transmission line to the to~ers o~ thi~ li~e; in which the electric field in a major portio~ of the inter-phase g~p extent is approximately uniform~ ~he configura-tion o~ t~e phases in ~he transmi~ion line con~idered is V-shaped with a~ included. angle of 120 at the apex~
which has enabled to group them around a com~on c~nter so that in each phase one straight arm of the V-shaped con-figuration of this phase is aligned parallel to one of the straight æ m~ o~ the V-shaped configuration o~ the second phase~ while th~ other strai~ht arm of th~ V~sha~
ped configuration o:f the ~ir~t pha~e is ali~ed paral~el to orl~ o~ the straigh~ arms o~ the V-sh~ped con~igura-tion of the thlxd phase~ In all o~ tho phases sunco~duc-tors are equidistantly spacad apart and one of the sub-conductors of each phase is disposed at the apex of the V~shaped co~iguration o~ the phase,, With a vi~w to r~-duce capacitive couplirlg wîth t~he ground in these condi-tions al~ o~ the phase s o~ the above t~ smission ~ine are positioned above the tbwe:r and secured ~hereto by means o~ post insulators.
~ he burldled phases OI such a tr~missio:n line are brought to each other at a les~e~ di~ta~ce as compared ~ 6 with other prior art txansmission li~es. However, by virtue o~ the fact that all the three bundlsd phases converge at the common ce~ter a~ the spacings between the subconductors in each phase are equalt th~ electric field in the area o~ the common center is not approxima-tely u~iform and, there~ore~ is subject to disruptiYe e~ects whenevex the line undar~oes overvoltages~ ~his re-sults in the necessity of limiting the power transmission capacity of such a line~ ~oreover, as it was pointed hereinabove, the use o~ post-type insulators ~akes it indispensable to decrease the spans and to e~l æ ge the number o~ suspension tower a~semblies,which inevitably adds to the cost o~ the transmission line a~d con~ines its application for transmission lines with higher voltage and capacity ratings provided with an appreciable amount o~ massiv~ subco~ductor~ 1~ each phaseO
It is an object o~ the pre~e~t i~vention to provide a single circuit three-phase overhead slectric po~er transmission line o~ ~he bu~dled-phase type ~eaturing an improved power transmission capacity.
Another object of the present invention is to provi-de high economic e~`~icienc~ characteristic~ in a hi~h, e~trahigh a~d ultrahigh voltage electric power trans~
mission line~ starting from a rated voltage o~ 150 ~V
and higher.
Still another object o~ the pre~ent inv~ntio~ i~ to decreas~ the width o~ a right-o~-way corridor occupied ~ 10 ~
by the electric po~er transmission ~ine a9 well as to ensure its relatively small ecological i~pact~
With these a~d other objects i~ view there is propo-~ed a single-circuit three-phase overhead electric power transmission line o~ the bundled-phase type compxising i~
combina-tion a pluralit~ oP conductors attached to metal-lic spacers defining the cross-sectional configurations o~ bundled phases in a plane parallel to the axis o~ the transmission ~ine, a series o~ towers whose struc~ura~
members are disposed outside the space occupied b~ the bundled phases and air gaps therebetween, and insulators ~-securing the phases of ~he transmission line to the to-wers of the a~ore~aid line in which the electric ~ield in a major portion of the extent o~ interphase gaps is approximately uni~orm~ wherein,~ according to the prese~t in~entio~, spacings between each pair o~ tower suspended adjaaent bundled phases in the cro~s seation ~f the transmission line, at lea~t, over a major portion of the le~gth of the a~oresaid phases, are equal, while subco~ductors in one or more phases are arranged not equidi~tantly so that electric charges o~ the subco~du¢-tors are equal~ and th~ electric ~ield ~ormed by th~
a~oresaid arrangement of the bundled phases and subcon ductors is approximate~ orm in the entlrQ extent o~ the interphase gap~, in whi¢h ~ie~d an e~ectric break-down o~ the interphase ~aps upon the appearance o~ ov~r-~ ~ , ........
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voltages in the transmi~sion line in e~ce~s of thosepermissible may occur exclusively in streamer ~orm9 ~ he streamer form of an e~ectric breakdown is k~ow.~
to represent a consecutive series o~ reproducible electxon avalanches i~ the in-te~p~ase spac0 displaced with respect to each other i~ time a~d space~ ~his breakd~wn ~orm is a~companied by tha development of a kind o~ wave proce~s~
in which the area of the highest ionization intensit~ mo-ve~ by mea~s o~ the determining influence of photoioniza-tion processes at a rate o~ 108 cm/s. ~he mean di~char~e electric gradient with the streamer form of a breakdown is higher than with the leader ~orm ~nd amounts to ~-5 kY/cm.
~hus, the streamer ~orm o~ a~ electric breakdo~n is a ~uan-titive measure characterizing the electric ~ield uni~ormi-ty degrea~ By vîrtue o~ the ~act that a breakdown in the entire extent o~ the interphase~ g~ps may occur onl~ i~
streamer ~orm, the present invention en~ures an optimum i~
crease in -th~ electric ~ield ~niformity~ Thi~ allo~s to raise considerably ~h~ transmis~ion capacity o~ hi~h~
extrihi~h and ultrahigh voltagq electric power transmi~-sion lines~
- At the same time it ls expedient that each pair o~
the adjacent phases b~ spaced apart so that the electric gradient in the interphase gap~ at an operating voltage varies from 1065 k~Jcm with a ~axim~m ove~voltage multi-plicity ~actor to 3.15 kV/cm ~ith a minimum overvoltag2 multiplicity factor in -the tra~smd~ion lineO

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~ 12 In one embodiment o~ th0 electric power transmission line of the present invention ha~ing subconductors of the bundled phase~ disposed i~ the cross section thereof all o~ the configurations can be executed in the form of a closed design. ~his design i3 pre~erable for tr~lsmission lines on which the highest surge-impedance loading is to be transmitted~
In the foregoing embodiment the number o~ su~conduct-ors irl the lower half of the configuration of at leask one exterior bundled phase should be made larger than tha.t in the upper ha~f o~ the co~i~uration of the phase in question. With regard ~or the pro~imity of the lower portion o~ the configuratio~ of the exterior bundle pha~e to the ground as well aS for its increased capacitance~
the above distribution of gubconductor~ is most pre~erred for matching char~es and cu~rent~ in the subco~ductors, improving a degree of the electri.c fiqld ~niformity and cuttin~ dow.n losses in the subco~duc-tor~.
It is expedient tha~ the closed configurations o~
bundled phases have the foxm of concen~ric ci~cles.
In tke electric power transmission line o~ the pres~nt invention the subconductors o~ one o~ tha bund~ed phases may be divided equally into two ~emiphases, the configuration of each o~ the aforesaid semiphases i~ the oross-sectional area of the txansmi~ion ~ine repre~enting a circle disposed inside the circle aro~nd which lie~ ona of the two other bundled phases. Such a desi~:n enabl~s to decrease the height o~ towers~
According to a principal embodimen-t of the electric power transmissio~ line o~e o~ the con~iguration~ around which the sunconductors o~ bundled pha~ss are disposed in the cross sections o~ the tr~nsmi~ion line7 ma~
have a clo~ed design9 while the rest may be executed open and embxacing the first confi~uration. It is expedient w~th the a~oresaid design ~hat spacings betw~en ~he sub-conductors in the miadle portion o~ the con~iguration o~
at least one open exterior phase be lesser than those in the marginal portio~s Q~ the con~iguration o~ the phase in question. This, as was stated hereinabove in connec-tion with the first-mentioned embodiment, allows i~ the simplest manner possible to match charges and currents in the subconductors as well as t~ decrease losses in ~hem and to improve a.degree o~ the electric ~ield uni-~ormity.
A particular embodiment whe~e one o~ the bundled phases has a closad con~iguration and the rest ha~e an open configuration is the case in which the co~figura-tion of the upper bundled phase i5 shaped like an oval~
while the con~igurations o~ the lower bundled phases are shaped like curves whose convex portion faces downward.
This enables to accomplish ~he suspension o~ the bundl~d phases on the lowers in the simple~t manner pos~ible~

, ~6~96 In the elec~ric power txansmission line of the pre~
sent invention the configurations o~ all bundled phases may have an open design. Such a design is preferable for transmission lines with a relati~el~ lesser surge-imps-dance loading as opposed to the îirst of the two a~ore~
said embodiment~ o~ the txansmission lines o~ the present invention. I~ this specific embodiment, with a viaw to prevent the occurence of local corona ef:Eects alon~s the edges oî the open con~iguration~ of the pha~es whe~ en-suring the matching of charge a:~d current in the sub-conductor~t it is pre:Eerred that the ~ubconductors i~
the middle portions o~ the b~:~dled-phase corL~iguration have larger ~pacings therebetween than -those of the sub-conductors dispo~ed around the marginal portion~ o~ the co~figurations.
The open configurations o~ bundled pha~es m~ be shaped like cu;~res whos~ convex portion face~ downward so as to ensure simplicity in suspending the bun~led phases on the towers.
~ o achiQve a larger decrease in the electric gradi-e~t under the transmission line as well as in the width o~ a right-of-wa~ corridor occupied thereby, the con~igura-tions o~ all o~ the bundled phases may have essentiall~r a vertlcal arrangement, in whi~h case the ~xtremitie~
of the ma:rginal bundled phase~ ~hou~d be bent in the dlrectiolls e~t~rnal to-thQ middle bundled phase, while the e~r~mities o~ the mlddle h~andled pha~e should be . .
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emplo~ed fox supporti~g the subconductsrs disposed a~ ong lines perpendicular in the cross sec-tion o~ -the tra~mi~~
sion line to the major portivn of -this bundled phase.
The ope~ con~igurations of bundled phases ma~ have esse~tially the ~orm o~ straight lines7 in which case the con~iguration~ oî all o:~ -the bundled phases having the ~orm of straight li~es can be arranged horizonta~ly or vertical~ he above~mentioned desig:~ is preIerable ~or the electric power tra~smission lines featurirlg a relati ~ely lower voltage level~ having no local corona ef~ect~
in the marginai pllase area.
In order -to matG~ the ~apaci~ance o~ alil the three bundled phases ~d to ensure in them a~ equal voltage drop it is expedient for the tra~smission lines o~ the present invention whoRe configurations o~ the bundled phases are essentiall~ shaped like straight lines, that the configu-ration of the middle bu~dled phase have a length les~e~
than tha~ of the confieurations o~ the margi~al o~es.
In the embodim~nt incorporating the ope~ oon~igura-tion~ o~ the bundled pha~es with a ver~tical arrangemen~
it is e~ die~t that their lower ex~remities be secured b;y mean~ o~ insulatoxs to a~ additional low~r transver~
member provided in -the tower as~emb~y. Thi~ ensures more reliable fl~ture o~ tho bundled phases preve:iltirlg thei:r~
away and thus allows ~o decrea~3e ~he width oî the suspe~-sion towers., .
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'16 In the electric power transmission line o~ the pre-sent inYention where the con~igurations of the bundled phases are shaped like circles disposed concentrically with resp~ct to each other, the suspen~ion towers may be e~ecuted with a V-shaped post, ~hich is pivotally coupled to the ba~e made o~ three inclined post~ diverging in plan ~rom a common center at a~ angle of 1~0 and rest~ng with ~heir lower end portions on base plates. In this tower assembly the upper end portions of the V-shaped post are connected to each other by one flexible tie mem-ber and also to the lower e~d portions of the inclined posts, while the latter are connected to each other by a common f~eæible tie member cap~ble o~ being drawn to a state o~ tensio~ from one point~ ~uch a tower i~ the lightest in weight and the least in metal consùmptio~
as compared with other tower assem~lies and it can be readily put to u~e awi~g to the a~o~esaid design and arrangement of the oon~igurations o~ the bundled phases as provided bg ~he present in~ention.
~ or the sake o~ convenience,, whi~e brirlging out the ~ubconductor~ of o~e bu~dled phase in the embodime~ts o$ the prasent invention where the cor~igurations o:E the bundled phas~ have a mut~ally em~racing and ~mbraced design, it i5 expedient that each dead eIld~ anchor a~d tower compri~e a~ ~eas~ one three-po3t gaxl~ry provided with tra~ verse members, struts alld rigid couplings~ while .

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' ' - " - '- .' ' ' -~ 17 -the subconductors in each bundled phase be secured by i~sulators to the struts and transverse members o~ the corresponding portion 0~2 by one~ ~tar-tin~ ~rom the subco~ductors of the phases disposed along a lar~e-dia-meter curve.
~ he esse~ce o~ the present i~ve~tion as ~el~ as ad-va~tages thereof will be ~urth~r e~plained by its pre~
f~rred embodiments illustrated in the accompanying dxa-wings.
~ he ~eatures of novelty of the prese~t inve~tion as well as the ~oregoin~ and other object~ thereof will become more evident from the co~sideration of its pre~e--rable succeeding embodiments gl~en b~ way of a~ample with descriptive reference being made -to the accompan~-ing drawings, in which:
FIG. 1~presents corre~ative relatio~hip betwee~ tho surge-impedance loading PSi o~ single-circuit three-phase overhead electric po~er tran~mis~ion lines o~ the bundled-phase t~pe and the number o~
su~conductoxs n in the bundIed phas~;
FIG. 2 preserlts alternative designs and re~pective arran gemsnts OI the bundl~d ph~e~ (a~b,c) :in sing~e~
circuit three-pha~e overhead e'lectriC power tr~-mission lines o~ the bund~ed-phase type and their corr~spondi~g diagratns (d) o~ t he surge-lmpedanc~
loading PSi rel~ed to the width B of the righ~

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,i 1~8696 - 18 ~
of~way route occupled b~ the line;
~IG. 3 presents relationship b~tween the 50% di~charge voltages and the 5O% disch~r~e intensities and the length o~ air gaps available between -the bundled phases whose configuratio~ i~ in the form o~
straight lines a~ pulse switching voltage surges with a ~ro~t length o~ ~OO mcs;
FIG~ ~ presents a single-circuit thre~-phase overh~ad electric power transmission line incorpora-ti~g bundled phases whose con~iguration~ are designed .in the ~orm of co~centrica~ arra~ged cira~es, according to the present i~ve~tio~;
FIG4 5 present~ the electric power tra~smission li~e shown in ~IG. 4, the exception being that the su~
pe~sion tower features a di~eront design~
FIG~ 6 presents the electri~c power traa~mission line show~ ln ~IGS.:4 and:5, the excaption being that the tower features still a~other desig~;
FIG. 7 presents the elsctric power transmission line shown in ~IGS~ 4, 5 and 6, the exception being that the tower ~eatures s~ill another desig~;
FIG. 8 presents a sin~le-circuit thr2e phase overhead eleotric power transmission ~ine G~ th~ bund~ed-phase t~ype, one o~ the~bundled phases being sub divlded ln~o two æemi:phases~ according to the present inventi~n;

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' ll~B696 _ ~9 _ FIG. 9 presents another alternative embodiment o:e an elec~ric power transmissio~ e according to the in~e~ion9 in ~hich the con~iguration o~ one of the bundled phasas ~eatures a clssed design, whil~ the con~iguratio~ of other bundled phases feature an open desi~n;
FIG.10 presents still ano~her alt~rna*ive embodiment of an electric power transmission line accordi~g to the invention, in which the con~igurations o~ all th~ bundled phases ~eature an open curve design;
FIG.11 pre~ents the electric powær transmi~sion lina show~ IG. 10, the eæceptio~ being that tha configuratio~ o~ all the bu~dled pha~e~ are de-si~ned essentia~l~ in the ~orm o~ hori~ontally arra~ged ~traight li~s;
~IG.12 pre~ents the electric power transmission line shown in FIG. 11, the e~ception being that the configuration~ of the b~ndled phases are arrang~d vertically;
FIG.13 pre~ents as assembl~ for ~ g the bund~ed phase~
in po~ition, accordi~g to the embodiment s~w:~ in FIG. 12, ill the: spa~ o~ the tra~missio~ ~ine;
FIG.14 presents the samo as i~ FIG. 11, but îor ~lec~rio power tranæmissio~ line~; having lower ~o~tage ra tiIlgs;
FIGo15 presents the same a~ in P~IG~12; bllt ~or aleotric ~L6~6~16 - 20 ~
power tran~mi~gion ~ines having lowex voltage ratlngs, FIG.16 present~ the dis-tributio~ o~ subconductors in the bundled phases o~ the electric power transmission line shown in FIG. 12;
FIG.17 presents a relationship o~ the mul~iplicity o~ the surge-impeda~ce loading PSi of the el~ctric Power transmissio~ 11nQ accordi~g to the invention and the surge~impedance loadi~g PSta~si of ventional ~tandard tran~mis~ion ~i~e o~ one a~d the ~ame ~oltage rating to the ratio o~ th~ length o~ the middle bundled phase to the di~tance S
between the phase 9;
FIG.18 presents a relationship o~ the surge impeda~Lce Z5 and the operating capacitance C of a si~gle-cir-cuit three-pha~e o~rerhead eleotric power transmi~
sion lino o:E the bundled-phase type to the ra-ti~.
I./S;
FIG.19 pre~ents a~ electris power transmi~sion line according to the invention, i~ which the suspen-sion to~e~ incorporate~ a V-shaped post ~or securi~g the bundled phase~, whose con*iguratio~s are desi~n-ed in the form;
~IG.20 prese~t~ an electric power tran~mission line according to the present ~ve~tion with a dead e~d tower~

:

FIG~ 21 presents the electric power tra~sMission line shown i.n FIG. 20 according to ~he present inven tion in section XXI and with a view gi~en along the le~gth of the axis of this ~ine~
For a more lucid i~sig~t i~to the nature o~ the present i~vention it i9 considered use~ul prior to -ths description of its pre~erred embodiment~ to dwell in some details on the theoretical background o~ the pre~ent ln-vention~
~ he general conditio~ concerning the economic effi-cienc~ of three-phase o~erhead electric power transmisslo~
lines consists in the e~ective uss of their subconductors, whose criterion is the ~ransmittal of electric powsr with economic-optimum current densities in the subco~ductors~
In conformity with th~ co~dition co~c~rnl~ the suppressio~ of corona dischar~e effec-ts to mai~kain co-rona losse~ radio interference~ noise level and the like within a permîssible range, the electric gradiant at the sur~ace o~ subconductors should not exceed the permissible grad~en~ ~ ~r depending o~ the radius rO
of a s~ngle subconductor, a plurality oI which consti-tut~ the b~ndled phases o~ a transmis~ioll line~
~ akin~ into consideration this condition~ as we~l as the ~ondition r~gardin&s the maximum utilization o.
subconductor ~urfaaes, the permisslb~e charge value ~per i~ the subGonductor ca;n b~ determined :E'rom the following formula:
21~ n F"~

where: n ~ number of subconductor i~ the bundled pha~e;
- air dielectric constan~;
~n ~ coe~ficie~t of nonuniformit~ in the dis~
t.ribution of the electric grad~ent at the surface of subconductors~
The co8:E:ficient ~ represents the product of two co~fficien~s ~n = E~1 ~Kn~ ~ (2) her~: Kn~ ~ coef~icient o~ nonuniformit~ in the di~tri-bution of charge over the single subconductors of a bundled phase equal to the ratio of a ma-ximum charge to a minimum charge, E - coefficient of non~ni~ormity in the di~tri bution o~ the e~ectxic gradie~t at the sur-~ace o~ a maximum.charge fiubco~ductor equal to the ratio of a maximum electric gradiant to a mean electric gradient ~or the give~
subco~ductor .
In order to make fullar use of the sur~ace of sub-conducto~s7 the operating capacita~ce C OI a tra~mi~-sion line should be such that at the phase vo~tage Uph the subconduc-to~ char~e would have the p~rmi~sib~e value ~ er ~ ~ ~8 ~ ~

C = ~ ~ (3) Uph Kn ~ UPh It is evide~t ~rom the foxmula (3) tha~ the opera~
ing capacîtance C should i~crease with an increase l~ the number o~ subcondu¢tors in the bundled pha~e.
The surge impedance Z~ o~ the transmission line is determined ~rom the ~ollowin~ ~orm~la:
Z = - - ~ (4) s V ~ C

where: Vw ~ propaga~on velocity o~ an electroma~neti~
wave alo~g the subconductor~, which i~ close to the ve~ocit~ of light and equal to about 3~108 m/~
Having introduced into the form~la (4) the~de~
tion o~ the operating: capacitance C-through the ~ormula ~3)9 the above val~e will be obtained as ~ol~ow~:

z = _ _ _ 60 En Up 2Jr~o VW~n-ro æper n rO^~p~r ~ he surge-impedanoe loading P~i o~ the e~ectric po~
~wer txansmi~sio~ line can be determined from the k~own ~ormula with regard ~or the ~ormula (5) a~ ~ollows:
: 3 ~ph ~ (6~ :
~s 20.Kn .- ~

.

-, ~

- ~4 ~
I-t tra~spire 5 from the ~ormula (6) that with the conditio~ co~cexning the maximum utillzation of subcon-ductor sur~aces~ depending in turn on ~he uniformity in the distribution o~ charg~s and curre~ts in the subco~
duc-tors, the power being transmitted on a three-phase alternating-current transmission line is directly pro~
portional to the number o~ subconductor~ n and can in-creased at one and the same vol~age ~eve~ theore-ticall~
to i~inity~ In this case the speci~ic surge-impedance loading P~p ~i calculated per one æubconductor will amount to:

P~;P-Si = B3- _ ~g.r P~ ~7) Referri~g now to FIG. 1, there is plotted on the x-axig the ~umber n o~ æubconductors in thc bundled pha~e; while on the y-axis i~ p~otted the surge impedance k~J
loadi~g P~i in ~ o~ sing~e-circuit three-phasa overhead electric power transmi~sion llnes having the same voltage ratin~ of 500 kV. In a~l o~ these transmis-sion lines use has been made o~ ~ubconductors of the steel-alumirlum type, the alumi~um portion being ~40 mm~
in cross s~ctional area, their ou~er diame~er being equal to 2~ 24 cm; and inner diameter o~ the stea~ co~e being equal ~o 0096 cm.
~ he straight line t in ~IG. 1 show~ the theoretical limiting surge- impedance loadings o:~ the tra~smission : .
, ~ .
..

~6~6 - 25 ~
li:nes upon increasing the number of subconductors in the bundled phase ~d arranging them in an optimum manner aro-und optimum~diameter circles1 their subconductors being suspended at the same heigh-t. The cur~e "a~' shows ~he surge-impedance loading of the lines using ~he s-tandard generally accepted arrangemen-t o~ the bundled phase~ and subco~ductors therein (h'I~. 2-a); where the subconductors of each phase are disposed around a circ~e havi~g the ra-dius o~ bundling rb = 0~4 m~ 3 ma~ be seen from the cur-ve "a" (~ 1), with an increase i~ the number n o~ sub conductors of the transmission lines in question their surge-impedance loading values tend -to increase, but they do so quito insignificantly. ~hus, with n = 10, the surge~
~ ku~
-impedaIlc~ loading will amount to 1.125=E~.I~ which make~ a 26% increase as compared to the conven-tional transmission line where the number o~ subconductors ~n tho bundled phase is equal to 3 and whose sur~e-impedance loading amounts to 900 megawatt at a vo~tage rating o~
500 kV; With an increase in the radius o~ bundling rb to 0.7 m (~IG. 2 b) and th~ number o~ su~conductors i~ tha bu~dled phase being equal to 10, the surge-impedance loading PSi gains a somewhat larger incr0ase (the cu~ve "b" in ~IGo 1) aB compared with th~ transmission ~ine having the radius o~ bundlin~ equal to 0~4 m, which in this particular case makes a 5~0 lncrease. However, such an ~ncrease in -the surge impedance loading l~ al~o ~alr~

.
. .

.
. ' , - 26 ~
insigni~icant and does not permit to mak~ optimum use o~ the subconductor saction. It is on~y with an increa~
in the radiu~ of bundling up to 2.5 m and a respective increaSe ln the number o~ subconauctors up to 10 that there can be achieved the ~h~oxetically ~imiting surg~
impedance loadi ~ o~ the tran~mission line coming to about 2.7 ~ w~-, or ~r~e time as much as compared with that of the co~ven~ional standaxd transmission line ~FIG. 2-a) with a vo~tage ra-ting o~ 5OO kV, Eowever, with such an increase in the diameter of the bundled phases up to 5 m, the overall dimensions o~ the tower assemblie~ used also tsnd to considerab~ increase as opposed to the conventional standard trR~smissio~ li~9 5 m in height and 15 m i~ widtho ~s a resu~t, such a transmission line becom~s unnecessaril~ cumbersome and expensive, and, there~ore~,uneco~omical.
~ rom the above con3idsratio.ns ~ollows a corclusion -., that an increase in the surge-impedance loading o~ the transmis~ion line obtained by mean~ o~ a mere i~crea~e in the number o~` subconductors in the bundled pulse, or eve~ b~ means of an increase i~ the number of subconduc~
toxs a~d in the radius o~ bundli~g, is economica~ly unreasonable ~or conventional ~tandard li~æ.
~rom the ~ormulae ~6) and (4) there ca~ be in~rr~d:
Pæi = 3~UphVw'a ~8) It transpires ~rom the abo~e interrelationship that th~ surge-impedance loading of the electric power trans mission lines is directly proportional to its operatin~
capacitance C. As applied to the conventio.nal standard lines where the subconduc-tors incorporated in the bu~dled pha~es are disposed around circles separated in a hori-zontal direction, the operating capacita~ce is approxi ~ately derivable ~rom the following relatio~ship:
~o a~f z~ (g) h Z~
here D - a~era~e geometrical di0~ance between the axes of the subconductor~ of di~ere~t phases.
As may be see~ ~rom this relationship (9), with a~
increass in the number o~ subco~duetors in the bundled phases singly or in combination with an increase in the radius rb ~ bu~ding, the operating capacitance C increa-ses dependlng on the logaxithm 0~ a change in the ~ore-going~ values n and rb and, consequen-tly3 varies rather slowly. ~his is why~ as it was already demonstrated h2reinabo~e, the surge-impedance loading o~ the tra~s-mis~ion line with an increase in the number o~ subcon-ductors in the bundled phase singly or in combination with an i~crease in their radiu~s o~ b~ndling varies in conventional standard transmissio~ lines quite in~
su~iciently i:n order to compensate ~or additionaJ~ expen-ditures.

2~ -~ he above conclusions suggest that a~ inc~ease made i~ the number o~ subconductors i~ the bundled phases with a view to enlarge the surge-impedance loading in the co~-ventional standard electric power tra~smi~sion line~, despite the theoretical substantiations~ has not yie~ded the desired results due ~o the ~ailure in en~uring satis-~actory economic characteristics o~ such traasmissiQn nes.
~ he present invention is based o~ a dif~erent way of increasing the surge-impedance loading o~ a transmi ssion line.
As it wa~ stated hereinabove, ~rom the ~ormula ~8) it follows tha~ the surge-impeda~ce ~oading o~ the transmi~
sion li~e is directl~ proportional to lts operati~g oa-pacitance. With the conventio~al sta~dard~ designs a~d re~pective arxangements of the bundled phases, the opera-ting capacitance upon a~ increase in the number o~ subcon~
ductors in these phases is growing slowlyO ~owever, the oper~ing capa~itance i9 a~so kno~n to depend on the oon~iguration and rcspective arrangemen~ of the bundled phases in the alternating-current transmis~ion line. It ~ollows from the above that with a certain configuration and respective arrangement o~ the bund~ed phases the operatin~ capacitance of the transmi~sion line can be caused to have a directly proportional dependence o~ the number o~ subconductor~ in the bund~ed phases in accord a~ce wlth the formula ~
.

~ particular solution to this problem has been dis-closed in ~he above~mentioned six-phase and three-phase electric power transmission lines o~ U.S.Pa~ent ~o.

3 . 249 . 773, wherein this solut ion c onsisted in bringing the phases c~oser -together. Eowever, ~his prior art transmission line has not solved the problem completel~
inasmuch as the con~iguration and respective ~rrangement o~ the phases ~ailed to be op~lmal, which was alrsad~
poin~ed out hereinabove, I~ keeping with the e~pounted e~sence of th~ presen-t invention each pair of adjacent phases is not only brought into proximit~, but al~o is essentiallg arranged ~:
over the entire extent o~ the phase~ at equal di~tances, while subconductors in the bundled phases are spaced apart so as to e~ure therein approximatel~ equal charge and current values. ~he conducted inve~tlga~ion~ have revealed that the mean operating capacitance C of such an ~lectric power transmission lî~e i8 approximatel~ e~ual ~o:
C ~ 1395~ o ( ~ ~ ~9) ~ ~10 where: ~ -'distance between adjacent bundled phases;
1 - length of the ~pace~along the co~figuration~
o~ the pro~îmate phaqe~ m~asured by the middle phase~
It ~ollows ~rom thi~ ~ormula (10~ that the operating capacitance of the electric power tran~mis~ion line accor-, ~ 30 ~din~ to the present invention is inversely proportional to the distance betwee~ the adjacent bundled phas0so ~ n appro2imatel~ uniform electric field7 which is created in the entire interphase extent o~ the transmi~
sion line of the invention comp~ying with the relation-ships (8) and (10), is quantit~-tiv~ly characteriz~d by that the electric dischar~e in this f`ield at voltage le~
vels exceeding the electric strength o~ the interphase air gap occure~ in streamer form, Shown in ~IG. 3 are the resu~t~ o~ a~periment&l in~
vestigations of the intexphase air gaps o~ one o~ the transmiSsio~ ~ines o~ the present inve~ion, in which the con~igurations o~ thc bundled phases are essentially designed in the form o~ vertica~ly dispased straight li~es (FIG. 2-c). On the x-axis in FIG.3 are plotted the di~ta~ces between the adjac;ent b~dled phases ~ maters~
and on the ~ axis are plot~ed the value o~ 50% discharge voltage~ U5o% in million ~olts (m~) and the value o~ 50%
discharge elect.ric gradients E50% i~ ~ilovolts per ce~ti~
meter (kV/cm).
~ he curve U în FIG. 3 shows the ~unctional depende~ce U5o% = ~ may be seen from FIG. ~, the 50~0 d~s-~harge elec~ric gradient repres~ted by the curve E
varies in the investigated tran~mission line ~rom 4.9 to

4.~ k~/cm depending on the distance SO Wlth al~owance made ~or safety ~actors ~or the level o~ overvoltage~ ~n - :

the transmis~ion line, which are into con~ideration inclu~
sive in the phase proximity e~ect caused by the wind, and g~aze ice9 the adjace~t bundled phases o~ the transmission line accordin~ ~o the i~ventio~ are c~pable 5~ being brought closex together -to such a ~istance S -that will provide the electric ~ie~d gradie~t in the interphase ~ap varying ~rom 1.65 k~/cm in the transmission lines with a maximum overvoltage multiplicity ~actor to 3~15 kV/cm in the transmission lines with a minimum over-voltage multiplicity factor. I~ this case the electric gr~ient at an op~rating voltaga is ca~cu~ated ~rom the formula:
Eoper = ~ ~ (11 ) ~here: Urt - rated voltage leve~ of the transmi~sio~
line;
2 - peak factor o~ the app~ie~ operating ~ol-tage.
Proceeding from the for~oing9 according to the pre-sent inventionS for transmissio~ lines with a rat~d vol-tage o~ 150 kV and ~n overvoltage multiplicit~ ~actor o~ 3.0, the lower limit of the e~ectric gradient ~0 i~
established equal to 1~65 kV/cm ana the dis~a~ce bet-we~n each pair o~ ~he ad3acent bundled phases respec-tively equal to 128 cm. For a tran~misslon li~e o~ th~
present invention ~ith a rated voltage o~ 1 150 kV~ l~

' .

which an overvoltage mu~tiplicity factor is 1.~, the upper limit o~ the electric gradient Eo is estab~ished equal to 3.15 kV/cm and the dis~ance betw~en each pair o~ the adjacent hundled phases respectively to 515 cm. ~he following data can be used ~or co~parison. I~ standard three-phase electric power -transmission li~es o~ the bundled-phase type who~e subconducbors are arranged around circles separated i~ a hoxizontal direction, the electric gradient ~0 amounts to: 0.65 k~/cm at a rated voltage of 500 kV and the distance between the adjace~t phases equal to 11 m; 0.69 k~/cm at a rated voltage of 220 kV/cm and the distance between t~e adjace~t phases equal to 4~5 m; 1.08 kV/cm at a rate vol~age of 500 k~
and the distance between ~he adjaoe~t phas~s eq~l to 6.5 m. ~he electric gradie~t Eo in the dsscribed ~
-phase transmission line with a voltage rating of 462 kV
and the distance between the adjace~t phases equal to 4.4 m amou.nts to 1.48 k~/cm.
~ he distances between the adjacent phases estab~ished in the tra~smission line o~ the present invent~on as wa~
speci~ied hereinabove ensure an adequate level of elec~
tric strength in the i~terphase air ga~, inclusive of the case when excessiYe wind loads come to be applied causin~
greater proximity of the phases within their acc~pt~d design values range. At the same time in order to e~-3ure a high~r operational reliabi~ity ~ev~l of the threaw :
' ~

9~

-phase transmission line w~th closely spaced bundled phases according to the invention by means of preventing their inadm~ssible proximity caused bv the wind, subconductor galloping the glaze ice disposal and subconductor oscil-lations, there can be accomplished some of the followingwell-known procedures, erection in the spans of a number of metallic spacers adapted for at-taching thereto sub-conductors of the phase, mounting of insulating spacers between the phases, securing subconductors of the phases in the spans to groun~ anchors by means of phase voltage insulated rods (cf. U.S.S.R. Inventor's Certificate No.
567,880 issued July 30, 1977 to Alexandrov et al)- Further-more, owing to a great number of possible configurations of the bundled phases and their respeetive arrangements aeeording to tne invention there can be ehosen such com-binations for specifie conditions and parameters which would ensure a minimum impaet of the wind on the phase proximity.

The above-mentioned procedures enable to aehieve smaller proximity distances between the phases of the transmission line. At the same time this is also faeilitated by reducing an overvoltage multiplicity faetor of the transmission line, for example, through the use of overvoltage suppressors, in particular, such as thosedeseribed in U.S.S.R. Inventor's Certificate No.
652,637 issues March 15, 1979 to Korsuntsev et al.

The three-phase electric power transmis~ion lines of the present invention colnplying with the above-st~ted theoretical substantiations feature the following per~or-mance a~d economic e~fiGiency figures.
Shown i~ FIGo ~ is the curve "c" characteriæing the surge-impedance loadi~g capable o~ being transmitted at a voltage rating of' 500 kV on the transmis~io~ into according to the i~ention whose diagram is presen~ed in ~IG. 2~c, depending on the number '~n" oP subconduc-tors in each bund~ed phase. As may be see~ ~rom FIG~ 1 with the number o~ subco~ductors in each bundled phase reaching 10, the surge-impeda~ce loading o~ tha -tr ~ ~-mission lines according to the inve~tio~ amounts to 2.6 mln.kwt, i.e~ rather close to the thsoretically possible limit equal to 2.7- ~ , and may coincide therewith at an optlmum value of the coefficien~ knO
Shown in FIG. 2-d are comparati~s graphs o~ the surge-impedance loadlngs o~ the txanæmission lines, whose diagrams together with their dimensions are give~ in FIG. 2-a, b, c, related to the width of the right-o~-way corridors occupied b,y these lines. In FIG. 2-d the width of the right-o:E-way corridors i~ plo~ted on the x~axis, while the density Bi 0~ the power transmitted on the line is plotted o:~ the ~-axi~. ~he area of the reckan~;les shows the surge-impedance loadings OI the traIlsmission lines according to their designations in the upper part of FIG. 2~ ~s ma;y bs ~een from the graph 2-d~ the surge-impedance loading o~ the transmission line 2~c according to the i~vention is considerably higher tha~ that of the conventional standard -transmissio~ lines 2-a and 2~b. ~t the same time, the width oP the right-~o~-way corridor o~ the transmission line 2-c according to the inven-tion is co~siderabl~ smaller than the wid~h of the rig~ -of~
way corridor~ oCcupied by the con~entional ~tandard trans-mi~sion lines 2-a and 2-b.
Illustrated in ~IG. 4 is one of the possible single--circuit three-phase overhead elec~ric power transmission lines of the bund~ed-phase type construc*ed in accordance with the prese~t inventlon and particularly suitable for use at highj. sxtrahigh and ultrahigh voltags~.
This electric power transmission line co~prises three bundled phases 1, 2 and ~j~ each incorporating 12 si ngle subco~ductors ~. ~he subconductor~ 4 o~ each phase are attached to metalllc members 5 *abricated from a light metal, such as an aluminum allo~ ~he metallic members 5 ~orm con~igurations o~ the bundled phases in a plane perpendicular to -the axis o~ the transmission line.
As may be seen from FIG~4, ~he spacers in the example considered have an annular form so that the confi~ura;~
tions o~ the bundled phases 1~ 29 3 are closed in desi~n and shaped like circles~ ~he me~allic mem~ers 5 are inter-connected by insulator~ 6 mak~ng up an in~egral ~tru¢ture and secured by suspension-t~pa strings o~ insulators 7 to ::

`~

i96 a suspension tower assembly ~, whose s-tructural members as may be readily seen from the drawing, are disposed outside the space occupied b~ the phases and air gaps therebetween. Al~ o~ the circles, representing the con-figurations o~ the bundled phases, are dispo~ed concentri-cally so that the distances S separating the bundled pha-ses o~ two tower assemblies suspended from the towers o~
the adjacent bu~dled phases 1-2 a~d 2-3 are equal over the entire extent of the configurations o~ these phases.
~he distance S is chosen such that the electric gradieD~
between the bu~dled phases in each of the a~oresaid pairs ranges at an operating voltage from 1.65 kV/cm with a maximum overvoltage multiplicity factor to 3.15 kV/cm with a minimum ov~rvoltage multiplicity ~actor i~ the tran;~
smission line.
~ he number o~ the subconductors 4 in ths e~ampla con-sidered, as it was already pointed out hereinabove, i~ the same in all o~ the bundled phases 1, 2 and 3~ However~
their distribution over the configuration o~ these bund-lad phases is not the same~ Thus, the subconductors 4 in the bundl~d phases ~ and 3 are disposed ~ith the same pitch. However, the subconduc-tors 4 included in the e~te-rior bun~led phase 1 are disposed ~ith a dif~erer~t pitch~
Thi~ is apparent ~rom ~IG~ 4, according to which in the upp~r hal~ of the con~lguration o~ the e~te3:ior bundled phase 1 are i~corporat~d ~i~e subconductors and in the lower half thereof are incorporated seven subconductors~
~rom which ~ollows that the subconductors in the lower half of the con~iguration of the e2terior bundled phase 1 are disposed wit.h a smal~er pitch than in its upper hal~. With such a distribution of the subconductors 4, the electric charges and curre~ts in them are close to their mean values~
With the above-described design the electric field in the entire e~te~t o~ the interphase gaps is approxima-tely uniform, the electric fie~d being liable to an elac~
txic breakdown upon the occurence o~ overvoltages in the line in excqss of those parmissible rather in streamer form than in any other.
~ he ~oregoing insulators 7 may comprise both strings of disk insulators and stick insulator~ as Well7 for example, poxcelain or fiberglass insulators. ~he insu~a-tors 6 may be secured to the more remote rather than to the n~arest poin~ of the an~ular metallic spacers 5 so a~ to ensure insulati~g strength both through the air and through the path of leakage in the insulating rod~
the latter may have a corrugated sur~ace or be arran~ed in much tha same way as the spokes of a bicycle wheel for enlarging the len~th of the path of leakage.
~ he strength of bhe metallic members 5 and o~ the insulators 6 and 7 sho~31d be de~igned îor ~he weight o~
all the subeonduotor~ of o~e ~pa oï the transmission line with allowanc~ made ;Eo:r the weight OI glaz~ ice.D

.

8~6 ~ he suspensiQ~ tower shown i~ ~IG. ~, from which are ~uspended the bundled pha~e~ 1, 2 and 3, is pxovided with two posts ~ i~clined outwardl~ ~rom the axis o~ the transmission line and resting upon hinges 9 fixed to fou~-datio~S 100 'rhe upper portion~; of the posts 8 are inter-Connected by a transverse member or a ~legib~e coupling 11. To keep the posts 8 in ths required position there are provided e~ternal 12, 13 and in-ternal 147 15 braces~
~he external braces 12 and 13 ar~ axranged in two rows a~d secured with their lower ends to anchors 16~ The upper ends o~ the braces 12 are connected to the upper portions of the posts 8, while the upper ends o~ the bra-ces 13 are connected to the middle portions o~ the posts 8. The lower ends o~ th~ braces 15 and 16 are secured to the foundation~ 10, while their uppe~ e~ds æ e connec-ted to the middl~ portions of the posts 8 at connection level of the same to the uppex ends o~ the braces 13~
As ma~ be seen ~rom the drawing, s~rings of the in-sulators 7 are attached to the upper extremities of the posts 8 and arranged at an angle o~ about 120. ?hl~ per-mits -to abate wind-induced swaying of the bundled phases SUSpended from the towers and to d~crease thereby spaeings betwee~ the po~ts 8~ At the same time the meta~lic mem~
ber~ 5 and the insulators 6 guard the subconductors 4 and the bundl~d phases 1, 2 and 3 against coming together into closer proximity.

-.

To prevent an inadmissible degree of pro~imity bet-ween the subconductors of different phas0s as well as cro~sing~ o~ the subconductors of one phase the spans o~ the t~ansmission line1 the~ can be provid~d with me-tallic spacers and insulators similar to the me-tallic members 5 and insulators 6 but o~ a lighter type, inas-much as they do not experience loads from ~he weigh-t of ths ~ubconductors and the forces applied thereto are in~
significant. ~he distance between su¢h spacers and insula-tor~ in the spans are chosen such -that tha phases are brought closer together a~o~g the length o~ ~he line in the spans, this being incident to relieving the subconduc-tors of glaæe ice or to their osci~lations under the acti-on of wind and other ~actors, quite to an insi~ni~icant deg-r~e and the remaining distance between the phases is suffi clent in all events to ensure the i~sulating strength.
In the above-described electric power transmission line the towers are furnished with one or two light~i~g protection cable support structures (not shown in the dr~wing). One or a few subco~ductors of this transmission line may be insulated ~rom the metallic structures ~or u~ing them as commu~ication links. ~here axe a~ple possi-bilities ~or application of other u~ual supp~ementary means emplo~ed in the known ~t~ndard transmission lin~s.
Due to the fairl~ small di~t~nce between the adja~
cent bundled pha~es afford~d by the provision thexebe-tw2en ~ 40 -o~ an appxoximatel~ uni~orm electric field the single-circuit three~phase transmission li~e of the bundled-phase type as described hereinabove exhibit~ an increased operating capacitance and9 consequen-tly~ a decreased sur-ge im~edance together with an improved surge-impedance loading.
As a specific e~ample consider the electxic power transmisæion line with a volt-age rating o~ 500 k~, in which the confi~uration o~ the inner b~ndled phase is 1 m in diameter, the adja¢ent bundled phases are separated from each other by a distance o~ 2~5 m, the co~igura-tion o~ the middle bundled phase is 6 m in diameter and 18.9 m in length. Each bundled phase in the transmisæion line considered is composed o~ 26 æteel-aluminum s~bconduc tors haYing a total cross~sectional area of the aluminum portion e~ual to 400 m ~ an outer diameter o~ 2.g cm and a diameter of the steel core equal to 1.25 cm1 the econo-mic-optimum current density bei~g o~ the order of ~ ~/mm2.
Such a tran~mission line constructed according to tho in~ention, as i-t was described hereinabove, has a surge--impedance loading reaching 3 mln. kwt, i. e v nine time~
as much as that of the conventional sta~dard 50)-kV tran~-mis~ion line whose surge-impedance loadin~; amou~ts to 0.9 m~n~kwt~
Anothex speci~ic example in~olves the electric power tran~mission ~ine with a voltage rating of 350 k~ constru-cted according to the inYen-tion and show~ in FIG. 4; in which the configuration of the inner bundled phas~ is 0,7 m in diameter~ -the adjacent bundled phases are sepa~
rated f'rom each other by a distance o~ 1.5 m and the con~
figuration o~ -the middle bundled phase is 7 m in length.
Each bundled ph~se in the transmission line considered is composed of 1~ steel aluminum subconductors having a total cross-sectional area of the aluminum portion equ-al to 2~0 mm2, an outer diameter of 2.2~ cm and a diameter of the steel cor~ equa~ to 0O94 cm, the economic-optimum current density being o~ the order o~ 1 ~/mm2. Such a transmission line has a surge-impedance loading reaching 1.8 mlnOkwt, i.e. 5~9 times as much as that of the con~en-tional standard 330-kV transmission line whose surge-impe-X /~ G ,,~ ~
dance loading amounts tc 0.36=~#~b~F
The foregoing e~amp~es ~how t~at the si~gle-circuit three-phase overhead elec-tric power transmission line shown in FIG. 4 displays surge-impedance loading ~'igures b~ .far superior to those o~ all the known alternating-current transmissio~ lines, the pre3ent transmission line being also rather compact in structure 7 which ensure~ its hi~h economic ef~iciency factoxs.
In the electric power transmission line illustra~ed in FIG~ 4 and described i~ the above example onl~ one of the possible t~pes of suspension towers has been outlined, Haw~er, lt iæ to be u~derstood that in the fore~oing 8~G

arrangement of -the ~undled phases as well as in the man~
ner of their han~ing from the suspension tower thera may be also successfully used other types o~ towers without impairing high per~oxmance and e*ficiency characteristic intrinsic in the above embodiment of the transmission line according to the present in~ention. ~hus~ shown in ~IG. 5 is the use o~ a portal type tower 17 provided with a straight horizontal transverse member, i~ FIG. 6 is the use of essentially a portal-type tower 18 pro~i-ded with a rounded transverse member, in FIG. 7 is the use of a V-shaped tower 19 provided with posts co~vergi~g at the base~
~ he subconductors 4 in all o~ the proceedi~g and succeedin~ embodiments are attached to the me~allic mem-bers 5 by means o~ clamps 20 (only one such clamp is con-ventionally gi~en in ~IGo 4)~
As in the case of the ~ower types indica~ed in this example, the axranget~lent and the number o~ the insulators 6 and 7, depending on the voltage used in the tran~miss-ion line and the climatic conditions pec~ r to tha line route, may ~i~fer ~rom the embodiment~ shown in the drawings and di~cussed in the preceeding a~d succeed~
ing egamples, but in all events they should provide reli-able fasteni~g of the subco~ductors and their i~sulation.
Shown in .FIG. 8 is another embodime~t of the elec~
tric power transmission ~ine according -to the present invention. Its structural e~ement~, analogous to the ele-ments of FIG. 4 are designated in the drawing by the same .
.

-l~B696 -- ~3 --~umbers.
In ~he e~ample condidered, just as in the case o~ the previous one, the co~figurations of the bundled phases are c~osed and designed in the form of circles, However, on~
o~ the bundled phases in this particu~ar example is di~i~
ded into two sémiphases 3a and 3b, the configura*io~ o~
each such s~miphase also representing a circle a~d each of these semiphases comprisi~g the sa~e numbar of single subconductors 4, in particular, six sub~onductor~ ~th the total number o~ subconductor~ in each bundled pha~e equal to twelve~ As may be ~een from the drawing7 the semi~
phases ~a and ~b are arranged insid~ the con~iæuration~
of the bu~dled phases 1 and 2, reæpectivel~. ~he cixcles o~ the configurations of the ~emiphases ~a and bundled phasè 1 and the circle~ o~ the con~igurations o~ -the semiphases 3b and bundled phase 2 are disposed concen~
trica~ he di~tances S and the dls-tribution of the subconductors in thQ egterior bundled phase~ 1 and 2 ~r9 establi~hed in much the ~ame manner as in th~ above-described example ensurirlg the:provision of an approxi-mately uni~orm field, the electric f~eld thus produced; .
being liab~e upon the occurence o~ overvoltages in the line in excess of those permisslble in no oth~r but in streamer ~ormO
At the t~rminals of thc tran~mission line, or at some other appropria~e points, the semiphases 3a a~d 3b are electricall~ i~tercon~ected.

:

':

~3~6~6 -- 44 ~
The rest of the structural elements of the trans-mission line are con~tructed similarl~ to the above exampleO
Shown in FIG. 9 is still another embodime~ of the electric power transmission li~e according to the inven-tion. Its stru¢tural elements a~alogous to the elements of FIG. 4 are designated in the dr~wing by the same num-bers, In -thi~ specific example one of the con~iguxations provided ~or arra~ging thereabout the subconductors o~
the ~undled phases in the cross section o~ the transmis-sio~ line, namely the con~iguration of the interior bund-led phase 3 has a closed design and represen~ an oval, while the co.n~igurations o~ the other two bundled phases 1 and 2 h~ve an open design a~d are shaped like curves embracing the configurations o~ the bundled phase 1~ As may be ~een ~rom the drawing, the con~igurations o~ the bundled phases 1 and 2 are arranged on the underside so that their convax portions are ~acing downwards. I~ i~
also evident ~rom the drawin~ that the outline o~ the transmission lina in this ~xa~ple appears to be as thoQgh derived from ~IG. 4 by cuttlng and ~epar~ting the t~o ex-tarior~phases.
Each o~ the bundLed phases 1, 2 and ~ comprises ln this example ~i~taen ~ingle subcorlductors 4., Howe~rer~ the number o:E ~3ubconduc~0rs in the mi~dle 2 and in the lower - 45 ~
1 bundled phases9 or in one o~ them, may be ~arger than in the upper `bundled phase 3, which seems expedient due to the high oapacitance o~ the lower bundled phases on account o~ its greater dimensions and/or to the compara-tivel~ increased capaci-tance o~ the middle bundlea phase 2 o~ accou~t o~ its disposition between the two bund~ed phases 1 and 3. S~ch bundling o~ -the phases where the number of subconductors 4 is unequal will enable the cur-rents to ~e uni~orml~ distributed over these subconductors and to gain thereby a decrease in the losses o~ power in the transmission line.
As ~a~ be seen from the drawing, the subconductors 4, both in ~he middle 2 and in the lower exterior 1 bundled phases, are arranged about the configurations o~ the phases in question with different pitches. ~hus~ in the middle portion o~ th~ co~igurations of the bundl0d phases 1 and ~ the subconductors 4 are s~parated ~rom each other by a smaller distance as compared wi-th the arrangement o~ thc subconductors 4 with respeot to each othex in the marginal portions o~ the con~igurations o~ th~se phases.
~his ~llows the charges and currants to be distributed in the subconductors ~ in a uniform manner, ~urthermore, a decrease ln the distance between the subconductors at the termiIlal portions of the open con:Eigurations o:~ tha burld-led phases 1 and 2 permlb~ to bal~ce the e;Leotric field gradient at th~se -terminal portion~ and enables to abat~

-so-called l~end eff`ect" preventing thereb,y the ~ormatio~
of local corona ~t the peripheral subconduc-tors o~ the bundled phases 1 and 2. For the same purpose the marginal portions o~ the bundled phases 1 and 2 are provided on both sides from the metallic spacers with sirlgle subcon-ductors 4.
~ he provision o~ such meang for suppressing the undesirable "end e~fect" is especially important ~or extrahigh and ultrahigh voltage transmissi.on lines~
~ he distances S between the adjacent bundled phases 1-2 and 2-3 are e~*abli~hed in m~ch the same manner as in the preceeding exam-ples. Owing to this as well as to the above-specified configuration and arrangement of the bundled phases and single subconductors in them, the electric ~ield of the example cbn~idered, just as in the case of those giverl above, is approximately uni~orm in the entire e~tent o~ the interphase gaps, this electric field being liable to electric break down~ upon the occurence of overvoltagas in the line in excess of tho~e p~rmissible in streamer form only.
~ he suspended strings of the insulators 7 are con-nected in this embodiment to the end portion~ of the metallic members 5 of the open bundled phases 1 and 2 and extend to the corners and to the transversè member 11 of the portal-type suspension tower along the lines close to the tan~ent at the terminal por-tions of the con~igura-tions of the bundled phases 1 ~d 2.

.

, ~

~6 ~

The rest o~ the struct~ral elements of the transmis-sion line considered are constructed in the same manner as in the first example~
Shown in FIG~ 10 is ano-ther embodime~t o~ th~ ~lec-tric power transmi~sion lina according to the present in-vention. Its structural elements analogous to the eleme~ts o~ FIG. 4 are designated in the drawing by -the ~ame num~
bers.
In this embodiment all o~ the configura~ions provided ~or arranging thereabout ~he subconductors o~ the bundled phases 1, 2and 3 in the cro~s section o~ the transmission line have an open design~ As may be seen ~rom t-he drawlng the configurations of the bu~dled phases are shaped in this case e~sentially as curved lînes whose convex portio~
is ~acing downwards. It is also apparent from -this drawing th~t the outline o~ the tra~smission ~ine in cross section appears -to be derived as -~hough by cutting the upper pha~e in FIG. 9 and separating the ter~inal portio~ of all the phases.
In the example illustrated by FIG. 10 each of the bundled phases 1, 2 and 3 compri~es bwelve single sub-conductors 4~ However, as in the example il~ustrated by FIG. 9, the number o~ subconductors both in the ~iddle 2 and in the lower 1 bundled phases, or in one o~ them9 may be larger tha~ in the upper bundled phase 3, ~his again being done to achi.eve the mo~t ~ni~orm dis~ribu-tion o~ curre~ts i~ these subconductor~ As may b0 seen from ~IG. 10~ the subconductors in -the middle portions of the bundled phases 1 and 2 are separated ~rom each other by a larger distance -that the ~ubco~ductors in the ma~gi~al por-tio~s o~ the phases i~ question9 i.e~ in exactly the same manner as i~ the preceeding exampl0.
~ he distance~ S between ~he adjacent bundled phases 1-2 and 2-3 are established b~ analo~y with the above e~amples. The electric ~ield in the entire e~tent of the interphase gaps is again approximatel~ uni~orm9 the elec tric field being liable to electric breakdowns upon the o~curence of overvoltages in the line -ln excess of those permissible in streamer ~orm only.
As mag be seen from ~IG~ 10, the upper trans~erse member 11 has a polygonal structure. From the inclined sides of this transverse member 11 o~ the metallic spacer

5 with the subco~ductor 4 are ~u~p;~nd~d strings of the insul ator 7 whose inclination angle decreases Prom the upper bundled phase 3 towards the lower 1. ~he metallic spacers 5 in the example considered are not interconnected by in~
sulators, as was the case with the previous example~9 this being possible because the effect of wi~d is substantiall~
neutralized due to -the form of the configuratio~s o~ -the bundled phases 1, 2 and ~ as w~ll a3 to the arrangeme~t of the string o~ in~ulator~ 7~ Howrver, if speci~ic appli-cation conditions ma~e it necessary, in -this ex~mpl~ as in th~ previous ones there may be also used insulators bet-ween the metallic spacers as well as the metallic spacers provided with insulators therebetween in the spans o~ the transmission line.
- ~he txansmission line discussed, as in the case of the line shown in ~IG. 9) is intended ~or use with a lo-wer transmission capaci~~y as opposed to the line in FIGo4~
Shown in ~IG~ 11 is another modificatio~ of the elec-tric power transmission line according to -the inventionO
Its structural elements analogous to the elements of FIG.
4 are designated in the drawing by the same numbersD
~ he profile of the cross section o~ the transmission line in FIG. 11 approximates the configuration o~ the line in ~I~. 10, but di~ers from it in ~urther "linea-rization" of the con~igurations of the bundled phases 1, 2, 3. As may be seen ~rom ~IG. 11, the con~iguratio~s o~
the bundled phases 1, 2, 3 are represe~ted over a majo.r portion o~ the length by horizontally arranged straight lines.
In the exa~ple considered the number of ~ingle sub-conductors 4 in each o~ the bundled phases 1, 2 and 3~
their distribution and the distance S bet~een the adja-cent bundled pha~es of the pairs 1-2 and 2-3 ar0 the same as in the example correspondin~ to FIGD 10. For this reason the electric ~ield in the entire extent o~ the interphase gaps is again approximatel~ uni.~orm, the electrlc field being liable to breakdown upon the occu-rence o~ overvoltages in the transmiæsion line in excess of those permissible in streamer ~o~m onl~.
As ma;y be seen from ~IG, 11, suspension to~rers in this embodiment are constructed in the ~orm o~ two verti cal posts 8 resting on the hin~es 9 of th~ foundation~
10. ~he posts 8 have their upper ex*remities oonnected by the ~le~ible coupling 11 and are rein~orced by guys 12 a~d 13 secured to the anGhors 14. Mounted on the upper extremitieæ of the posts 8 and f~exible coupling 11 a~e lightnîng protection cableæ 210 Dependi~g on speci~
conditions9 the number o~ such lightning prot~ction ca~- :
les 21 ca~ very. A.~ may ~e seen from ~IG. 11, in tha example consi~ered the metallic spacers 5 with the sub-conductors 4 are attached by strings of the insulator 7 to the posts 8 o~ the tower assembly. Tha con~igurations of the bundled phase~ 19 2 and 3 and the arrangemen~ of the string insulators 7 are even more ~avorable in the given e~ample as compared with the example in FIG. 10 allowing in many case to discard the use o:~ insula-tors ~or coupling o~ the metallic spacers 5.
~ ike .in the preceeding example, the transmission line o~ the example c~n~idered is intended for use with a lower power transmission capa~ity as opposed to the line ~ustrated in FIG. 4. Howe~er9 the tran~misslon line of this type in comparisQn with t-he pr~vious one iB simpler in design.
, . , , ;~

.

, ~6~ 6 Shown in FIG. 12 is the electric po~er tra~smission line according to -the present invention~ in which the configurations o~ the bundled phases are open and shaped essentially like verticall~ arranged straight lines in ~IG. 12 the struc~ural elements o~ the line analogous to the elements of ~IGS. 4-11 are designated by the same numbers.
The profile of the trans~ission lino in FIG. 12 in the cross section is derived ~rom FIG. 4 as though by cutting all the circles, about which are arranged the subconduc tors of the bundled phases, alo~g a vertical line a~d sub-soque~tl~ straightening three semicircular halves.
~ he configuration o~ the middle bundled p~a~e 2 in th~S example represents a straight line segment on who e borders moun-ted perpendicular to the main metallic me~ber 5 are additional metallie spacexs 22 of a short lengthO
The co~igurations of the two mar~inal bundled phase 1 and 3 over the major extent of the length are str~ight~
but their terminal portions are bent outwardly with res-pect to ~he midd~e bundLed phase 2.
~ he meta~lic mem~ers 5 are secured in the given example ~o the tower with both ends thereo~: the upper ends of the metallic members 5 are secured, as usual~, by string~ of the insulators 7 to the upper transverse members 11 o~ the porta~ tower, while the lower ends of the metallic m~mbers 5 are s~cured b~ insuLators 23 to

6~6 an addi-tional transverse member ~4 provided in the portal tower. In the last-mentioned of` the aforesaid couplings there may be mounted dampers ~5~ such as spring dampexs, for the prevention o~ damage i~flicted on -~he insulator~
22 with rup-ture of one o~ the subconductors 4, As may be seen from ~IG. 127 the subconductors are separated ~rom each other in the middle portio~s o~ the configurations of the bundled phases 1, ~ and ~ b~ larger distances than in the marginal portions o~ the phases in ~uestion. In ordex to prevent the occurence of local corona e~fec~s the te~minal portions of the con~igura-tions of the bundled phases 1 and 3 are furni~hed with an additional subco~ductor bei~g arranged from the side o~ the me-tallic spacer 5 opposite to the arrangeme~t of all the rest subconductors of the respective bundled phase. '~he additio~al subconductors in the middle bund-led phase 2 are fastened to the ends o~ the metallic spacer 22. All these e~pedient~ undertaken in order to suppress the undesirable "end ef~ects" are particu~arl~
important ~or extrahigh and ultrahigh voltag~ transmis-sion lines~
~ he distances S between the adjacent bundled phases of the pairs 1-~ and 2-~ over the major exten-t o~ the length o~ the con~igura~ions are established in much the same manner as in the preceeding examples. Owing to this as well as to the a~ove-speci~ied configuration a~d ,~

'~ ~

i8~ 6 arra~gement o~ the bundled phases and singl~ subcon~uc~
tors in them, the electric field in the example con~id~
red, as in those described earlier, is approximatel~
u~iform in the entire e~tent o~ the i~terphase ~aps, su`ch an electric field bei~g liable to electric break-downs upon the occurence o~ overvol-tages in th~ line in excess of those permissible in streamer form only.
In this embodiment, as contrasted to the previous ones, the use of the insulators 6 betwee~ the metallio spacers 5 is indispensableO ~hese insulators 6 together with strings o~ the insulators 7 and 23 serv0 to prevent inadmissible proximit~ between the bundled phases 1~ 2 and 3 caused by the wind. So as to elimin~te thls inadmisr~.
sibls proximity of the bund7ed phases and crossing of the subco~ductors o~ one bundled phase in the spans o~
the transmi~sion line they ~ay comprise exactly th~ same metallic members 5 and insulators 6, but o~ a lighter type since they do not have to w~thstand weight loads o~ the subconductors. Insteaa o~ the ins~lators 6 in the spans o~ the transmission line there may be installed phaso-voltage insulated rods 26 secured to anchors 27 (~IG~ 13).
~ he above-deac~ibed electric power transmission li~e, as co~pared with other transmis3ion lines9 employ~
a narro~er right~of-way corridor a~lowing at the same time to ~chieve the same surge-impedance loadi~s as in.
the -transmission lines illustrated in ~IGS~ 9~

.
,. ' ' - ' ~

~6~3~9~

Shown in ~IGS. 14 and 15 are other alter~ative embo-dime~s o~ -the electric power transmissîon lines accord~
ing to the i~vention, in which the con~igurations of the bu~dled phases over the entire length are arranged along straight lines. As may be seen from the drawings, the profile of the cross sectlons o~ the transmission lines in FIGS~ 14 and 15 differs ~rom the profile o~ -the trans-mission lines in ~IG~. 11 and 12 in "li~e~rization" o~
the terminal portions o~ the bund~ed phase~
Each b~ndled phase 1~ 2 and 3 in both of these examples comprise ~ive single subconductors. Such trans mission lines ma~ be used for co~parati~ely low voltage levelsj ~or example, ~rom 150 to 220 kVs which adm-it o~
the use of subconductors of the diameter ordinaril~
possessed b~ subco~ductors in the tra~smission llnes of such a voltage level and with which the a~oresaid single subconductors are not sxposed to local corona effects. In the examples considered the di~tance ~ bet;
ween the con~igurations o~ the adjacen-t bundled phases 1 2 and 3 is established in much the same manner as i~ the preceeding examples, hsnce, the elect~ic field thus produced in the entire egte~t o~ the interphase gaps is approxlmatel~ uniform, the electric ~iel~ again being liable upoll the occurence of overvolta~es i~ the trans~
mission line in e:~cass OI those permissible in streamer fo~n only.

.
. . .

- ;. . :., :
: ' . . ' ' ', ~ ~ ' The transmiSsion lines shown in ~IGS 14 and 15 have a different arra~gement o~ the co~igurations of the bund-led p~ases 1, 2 and 3.
In the ^transmission line of ~IG. 14 the co~igur~t-ions o~ the bundled phases 1, 2 and ~ in th~ ~orm o~
straight line sagments are arranged horizontally9 while the metallic mambers 5 are secured by both ends the strings o~ the insulators 7 to the posts 8 of -the tower assembly. Such transmission lines in the majoxity o~ ca~
ses do not call for the use of insulators between -the metallic members 5 as well as in the spans of the line~
since the wind, as a rulet hlows parallel to the ground and practically does not cause the subconductors to come close together.
In the transmission line o~ ~IG. 15 the con~igurations o~ the bund~ed phases 1, 2 and 3 in the ~orm o~ straight line segments are arra~ged vertically, while the metallic members 5 are suspended with o~e end by the strings of the insulators 7 ~rom the transverse member 11 of the ~o~
wer~ ~he metallic members 5 are interconnected in this e~ample by the insulators 6. In the ~pans of such a transmission line there may be also mounted -the metallic members 5 and the insulators 6 o~ the light-weight type~
Inasmuch as the number of the subconductors in the bund-led phases and the length of ~heir con~lgurations o~
this transmission ~ine are smal~, ther~ is ~o need in the majorlty of cases for ~ecuring the ends o~ the me-. .
:' ' .

tallic members 5 by insulators, as was -the case in khe embodiment illustra-ted in ~IGS. 12 and 13.
In the electric power transmission lines according to the invention~ in which the configuratiorls of all the bundled pha~es ~eatur~ a closed design as show~ i~ FIGS
10-15, it is expedient tha-t the con~iguration~ o~ the middla bundled phase have a smaller leng~h than the con-~igurations of the marginal b~ndled phases 1 and 33 this being done in ordsr to match capaci-tancas and voltage drops in all o~ the phases of the trallsmission line 3 in which ~he capacitance o* the middle bundled phase 2 tur.ns out to be ~arger tha~ the capaci~ance of the marginal blindled phases 1 a~d 3. Owing to this the number o~ trans-position cycles decreases to the values corresponding to those o~ the standard lines~
Shown to scale in FIG. 16 along the length of the configurations o~ the bundled phases 1~ 2 and 3 is the arrangement of subconductors in these phases in accordan ce with the embodiment illus-trated in ~IG. 12 for the electric power transmission line having a vol-tage rating o~ 500 k~.
As m~y be seen ~rom FIGD 1G, the subco~ductor~ 4 in the middle portions of the bundled pha~es are separated from each other b~ larger di~tances tha~ in the margi~
portions o~ the phases in que~tion. As it was alread~ in dicated hereinabove~ such an arrangement o~ the subconduc~:
torS in the ~undled pha~e~ enable~ to match charges and . :
.

currents in the subconductors and tQ proYide thereb~ in the air gaps between the bund~ed phases an approximatel~
uniform electric fleld wi-th improved uni~ormity. Such a distribution o~ the subconductors in the bundled phases al~o permits to cut down the losse~ o~ power and energyO
Furthermore7 a greater degree o~ proximity achieved bet-ween the subconductors 4 along the marginal portions of the conf~gurations o~ the bundled phases allows to pre-vent the development of local corona eff~c-ts~
~ he length of the con~iguration of the middle bund-led phase 2 amou~ts to 300 m, while the length of the configurations of the marginal bundled phases 1 and 3 amount~ 3.5 m, i.eO the length of the configuration~of the middle bundled phase 2 is smaller than -the length~
o~ the configur~tions o~ the marginal bundled phases 1 and 3, which enab~es to match capaci~ances and voltage drops in all o~ the phase s of the transmission line to the value usually observed in the known transmission li-nes.
It may be also seen from FIG. 16 that th~ number of the subconductors in the middle bundled phase 2 is e~ua~
to twel~e, while in the marginal bundled phases 1 and 3 it is e qual to nine ~ S uch an incre ase in the ~umbar o~
the subconductors 4 in the midd~e bundled phase 2 permits to match the currents i~ the subconductors since the current in the middle phase 2 is la~ger thR~ in the mar-ginal ones 1 and 3 on account o~ the capacitîvc in~lu-.

ence exerted b~ both o~ the margina~ phases on -the middle phase All the fore~oin~ peculiar features specified with reference to FIG. 16 are especially i~portan~ whe~ the number o~ the sub~onductors in tho bundled phas~s is large~
One o~ the electric power transmission lines accord ing to the i~vention illus-txated in FIGS 12 and 16 displa~
ys the ~ollowin~ characteristic data~
~ his transmission line is operated at a voltage ra~
ting o~ 500 kV. '~he total ~umber of the subconductors 4 in the line is 30. ~he subconductors 4 are of the steel--aluminum type, the a~uminum portion is 240 mm2 in ~ec tion, their outer diameter is~ 24 cm, the steel core is O~9~ cm in diameter. Th0 bund~ed phases are separated ~rom each other by a distance of 3 m, the configurations o~ the marginal bundled phases 1, 3 is 3.5 m i~ length, the con~iguration o* the middle bundled phase 2 is 3.0 m in length. The middle bundled phase 2 comprises 12 sub~
conductors, each o~ the marginal bundled phases compri-ses 9 subconductors. ~he electric f`ield gradient at -the subconductor surface is 21.1 ~V/cm (active value~ the electric field ~radie~t under the line at huma~ height level is 9 kV~M. The corona loss value in such a line is 14 kV/cm. The right~o~-way corridor o* th0 lins u~der the subconductors is abou-t 6.5 m wi~e. '~he surge-impedance loading e~hibited by the li~e is about 2~6-~-E#~; i9~
3 times as much as that o~ the conventional standara tran~r 1 ~B6~6 ~ 59 --mission line of the same voltage r~-ting, whose surge--impedaxlce loading amounts to 9ûO MW~
In the thxee-phase ~lectric power transmission lines according to the invention ~eaturing open designs o~ the configurations of the bu~dled phases illustra~ed in ~IG~.
10-16 there may be selected any length ~ o~ the con~igu-rstions o~ the bundled pha~es depending on the distance S separating them~ ThiS makes it possible to obtain an~
~urge~impedance loading over a Yast ra~ge~ ~or example~
~rom 1 to 5 times o~ the multiplîcity o~ the surge impe-dance loadings o~fered by the standard transmi~sion lines o~ the same voltage level.
In all o~ the above~described embodiment~ o~ the electric power transmission line~ co~structed according to the invention among the most importance para~eters are such parameters as the distanca ~ between the adjacent bundled phases, the length ~ o~ the co~igurations of the bundled pha~es~ and the ratio between these two.
I-t is apparent from the ~ormula (10) that the opera-ting capacitance of the transmissio~ line accordin~ to the pl~esent invention i9 approximately direct~y propor-tional to the ratio of L/So ~his relationship is illustrated in FIGo 17~ where the ratio o~ ~/S is plot~ed on tho ~-axi~
and on the ~-axis i~ plotted the multiplicity o~ the sur~o -impedance loading ~ i OI the line~ according to the in-vention with respect to the surge-impedance loadi~g -- 60 ~
PStan~ of the conventional s-tandard transmission lines, Psi/pstand.si. The values o~ PStand si depending on the rated voltage level o~ the lines taken ~or~compari-son are given in the table below:

Urt. 150 2~0 330 500 750 1150 kV
stand si 80 160 359 900 ~000 5500 line length,100 200 300 800 1000 1500 km It may be seen ~rom FIG. 17 that the relationship P~i/PStand ~i = f (~/S) is close to the rectilinear one and the ~urge-impedance loading of the tra~smission line according to the present invention ca~ be varied over a wide range increasing it multiply a~ compared with the sur~e-impedance loading of the ~tandard tran~mission lines of the same voltage.
Having sel0ctsd an optimum vaLue o~ the distance S
between the bund`lsd phases ~or a given voltage level~ ~he-re is determined the length ~ o~ the con~ig~ration o~ the middle phase depending on the required surge-impedance loading of the transmission line and its multiplicity with respect to the standard tra~mission line. ~ost preferred at that a:re the tr~nsmis~ion lines accordi~g to the invention fe~turing an open design of -the configu~
ration o~ the bundled phases. I~ these lines there ma~ be 36~6 - 61 ~
selected any range of the multiplicity o.f PSi/PStand si~
starting ~rom 1 to 5~ iOec the range which ln the ovex-whelming ~ajorit~ o~ cases ls of practical interest, or greater.
Shown in ~IG. 18 are relationship between the basic values o~ C and Zsg affecting -the surge-impedance loading of the transmission line, and the ratio of ~/S~
The number o~ subconductor~ n in the bundled phases of the transmission line accordi~g to the inve~tion is determined from the ~ormula (10) and (3) as follows:

n = ~ (12) 2 ~ rO ~per Su~ming up the above-~tated it can be co~cluded tnat the design of the transmission line is accom~lished as follows. ~rom the given surge-impedance loading P9i and the voltage Uph is determined the cu~rent and ~rom the adopted eoonomic-optimum surrent densitg is determined the raquired total cross section o~ the subconductors in each phase o~ the transmission line~ In FI~a with consideratlon ~or a permissible level of volta~es, S is determined and then, ~sing the cuxve i~ FIG9 179 is determined the ratio o~ ~ a~d by -this ratio is ~ele~-ted the ~-en~;th T of the eonIiguration~ of the bundled phase s. ~urther, from the :e ormula (12 ) i~ determlned ~the number of the subconductors.

!
'' ~

-- 6~ -Subse~uent to -this, more accurate calculations are per~ormed with consi~er~tions ~or the electric gradient a-t the surface of all -the subconductorst the coe~ficient En and ~or other values with the configuration o~ the cross section of the transmission ~ine chosen by the values of ~/S and n. It should be no-ted that khe ~ubcon-ductors in the transmission line according to the inYen~
tion are selected so as to have one and the ~ame cros~
section for e.nsuri~g equal sagging o~ the subconductors in the spans of the transmission lines.
As can be in~erred ~rom the foregoing~ the electric power transmission lines according to the in~ention feat~ro a highly important ad~antage residin~ in that an increase in the number o~ subconductors in the bund~ed phases accompllshed without enlarging th2 overall dimen-sions of the cross s~ctio~ of the transmission line enab-les to raise the surge~impedance loading in conformity with the ratio approximating the theoretical onsO
Shown in ~IG. 19 is ~he electric power transmission lin~ according to the invention, in which o~ing to the arrangement of the configurations of the bundled phases in the form o~ concentric circles it becomes poss~ble to employ a dif~erent type of the su~pe.nsion tower in con-trast to those iLlustra~ed in the dr~wings and described hereinabove~ ~he ætructural alement~ indicated earlier in the drawings are designated în ~IGo 19 by the same numbers.

36~6 ~ 6~ ~
The -tower o~ ~IG. 19 comprise~ two posts 8 having a V-shaped arrangement and re~-ting on the hinge 9 of the base~ ~he base is composed of ~hree inclined posts 28 diverging in plan at an a~gls of 120 and suppor~ed by three surface base plates 29~ As may be seen ~rom FIG~19, one of these .inclined posts is disposed along the axis o~ the trausmission line~ ThiS is preferab~e both from the viewpoint of loads applied to the tower assembly and from the viewpoint o~ lifting the tower a~d laying it out along the axis of the transmission lineO
~ he upper extremi~ies o~ ~he posts 8 are intercon-nected b~ the ~e~ible coupli~g 11~ Each of the upper extremities o~ the posts 8 are addi-tionall~ connected to the lower extremities o~ the posts 28, whi~e the lower extremities o~ these posts 28 are interconnecte~
b~ a common flexible cou~ling 30, which i~ passed so as to permit being stretched tight from one commo~ point.
Such stretchin~ a~sures u~ orm tensions bo-th in all the portions of the flexible coupling 30 and in the ~`le-xi~le coupling 11 as well. At the same time the posts 8 and the inclined posts 22 axe also caused to be te~ionedO
A~l this enables to provide rigidity o~ the tower s-truc-ture and economical use o~ the material for the manu~ac-~ure of all po~t~ this being po~sible becau~ tho ~orces acting within them ar~ directed axlally.
The abo~e tower fe~tures excellent stabilit~ a~
the aggregate of the subconductors o~ the transmission 365~6 ~ine according to the in~ention has a considera~Le weight which fixm~ presses the tower to the ground.
Such a tower permits to achieve a 30 to 60% decrea~
~e in meta~ con~umption as compared with other known to~ers, inclusive also o~ those described hereinaboveO
Its another obvious advantage consists in the po~sibility of te~sioning the entire structure by means of a turnbuckle alone . Furthexmore 9 the us~ o~ the base pla-te~ makss the productio~ of ~oundations much simplar and less e~pensi~o.
Shown in FIGS~ 20 and 21 is a dead-e~d tower of the electric power tran~mission line according to the invs~tion7 in which the subconductors of the bundled phases in the cross section o~ this line are arr~nged about three concen tric circles. In such a transmi~sion line much di~ficulty is encountered in brin~ing out the subconductor~ o~ the bundLed phases with the use o~ conventiona~ dead-~nd tower~, in particular portal-type towers provided with one pair o~ posts~
~ he porta~-type tower iLlustrated in FIGS. 20 and 21 comprises three portaL portions 31, 32 and 33 (E`IG. 22) arranged one a~ter -the other along ~he axis o~ the tra~s~
mission line. '~hese portal po~tions sequentially decrease in height towards the en~ o~ th~ transmission line. The upper extremi~ies of these portal portions ~1, 32 and 3~
are ri~idly interconnected b~ a beam 34, while th~ low~r ~xtremities ther~o~ are ~upported by foundations 35. In order to ensure the stabilit~ and strength o~ the entire , ~ , .'~

~6~69Z~;

~ 65 ~
dead-end tower the portal poxtions 31, 32 and 33 are interconnected by rigid couplings 36, each OI such por~
tions 31, 32 and 33 being also additional~y provided wi-th rigid couplings 37 and 38 (~IGo 21) between ~he posts 8 and with braces 39~
The subconductors 4 o~ the bundled phases having their configurations designed in the fo~m of cirGles are secured pha~e after phase by stri~gs of strain insulators ~0 (FIG. 20), one ~or each subconductor9 to one of the portal por~ions 31, 32 and 33, this being dona so that to the portal portion 31 disposed ~irst from the side where the tra~smission line passes are secured the subconduc tors of the exterior bundled phase 1, to the secona por~
tal portion 32 are secured the subco~ductors of the middle bundled phase 2, and to the third portion portio~ 33 axe secured the subconductors of the interior bundled phase 3.
Illustrated in ~IG~ 21 is the dead-end tower i~
section across X~ I with a view towards the second portal portion 32~ FIGo 21 reveals the manner in which th~ interior bundled pha~e 3 ~s axrang~d i~ space and at what point~ the subco~ductor,~ o~ the middle bundled phase 2 are secured by the strings of the strain insulators.
Also demonstxated in FIG. 21 is the manner of briIlging out the leads of the phases OI the tran~mission into the substation (leads of the inl;erior b~dl~d phase 3 are not shown in the drawing ~or clarity)~, ~8~

Since all of the subconduc-tors o~ one phase possess the same po-tential and are secured at the ~uspen~ion towers and in the spans to the metallic spacers common to each bun~ed phase, all o~ ~he subconductors o~ one phase do not require any intermediat~d insulation bet-ween them, but they do require and must be -provided with such insulation ~rom the towexs and the subGonductors o~
the other phases~ For this reason from each por-tal por-tion 31, 32 and 33 suspended on each s-tring of the insu-lators 41 is a metallic spacer 42? each o.~ these thre~
metallic ~pacers 42 being common to all the subconduc-tors of one o.f the bu~dled phases. The subconductors 4 in eaGh bundled phase are connec~ed to th~ meta~lic spacer 42 by loops 43. ~he upper end o~ these loops ~3 is attached b~ clamps to the subconductors, ~reely lowered downward~
and subseque~t -to coupling of all the loops 43 of one phase by a metallic spacer 44 (~IG. 20) is secured to the respective metallic spacer 42 suspe~ded ~rom the tower. As shown in FIG~ 21~ -the uppex subconductors ~ay be connected by means o~ clamps and pieces o~ wire 45 to the adjacent underly~ng subconductors ~rom which the loop 43 is tapped. In this case the number o~ the loops 43 decreages, bub those o~ them which serve ~or connec-tion of a few subconductors to the meta~lic spacer 42 ma~
require en~arged sections~
The ~ubsonductors of each phase can be easi~ brou~ht ou~ from each metallic spacer 42 to the substation ~n hoxizonta~ rows 469 47 and 48 (:EIG. 20) respectively for the bundled phases 1~ 2 and 3O
A~chor a~d angle towers can ba built in a ~imilar manner, each o~ these towers should comprise two portals~
.each of the portals being in turn provided with three ri-gidly interconnected portal por-tions9 as it was mentioned hereinabove ~or the dead~end towerO
The ~oregoing anchor ~a~enings for subconduc-tor~ may be equally utilized not only in the t~ansmission lines with concentrically arr~nged configurations of the bund~
led phase~, bu-t al~o in the transmission lines illustra-ted in ~IGS. 9 and 10.
~ he surge-impedance loading or power tr~nsmission capacity o~ a single-circuit three-phase overhead trans-mis~ion line o~ the bundled-phase type according to the present invention ma~ exceed from ~ ~ew time to ten times and more the surge-impedance loading o~ the conve~tional standard lines of the same voltage level having a regular spacing b~tween the bundled phases. Because o~ its increa-sed CapaCitanCQ the transmission line according -to the invention can be -termed an "overhead line o~ the cable type" (O~C~ which is capable o~ superseding a ~ew s-tan-dard transmissio~ lines o~ the same voltagc with their total power transmisslon capacit~.
At the same time the transmission line accordin~ to the in~ention disp~ays high economic e~icienc~ ~actors~

, .

~8~ig6 68 ~
Indeed, the cos-t o~ th0 subconductors o~ ~he trans mission line o~ the invention and that o~ the standard line are the same since the subconductors in both cases ar~ S~LeCted by the eco~omic~optimum cu~rent denæi~y and thus thei~ total section and weigh~ wi~l be the same for both o~ the lines~ ~his circumstance is impo~tant enough, for the cost o~ the subconductors o~ the tran~mission line depending on its voltage amounts from 25% to 55% o~
the total cost of the ~ine.
In view of the fact that the subcond~ctors used in the transmission line o~ the invention and those used in the standard transmission line are identical, the lengths of the spans of these lines will be also identl-cal.
~ t the same time the cost o~ the ~etallic spacers in the range o~ the towers o~ the transmission line according to the invention wi~l be higher tha~ tha-t o~
the standard line, but equal to or lower in comparîson with a few standard transmission lines of the same total surge--impedance loading as one transmission line o~ the i.n~en-tion. ~he provisio~ of light metall1c spacers and insu~a-tors in the spans o~ the transmission line according to the invention adds to the cost of the lîne ~uitei in3.i~
~icant~ ~nd does not a~e~t in any way sagging o~ tho subconductors a~d th~ len~th o~ the spans.
~ he total cost~o~ the tower assemblies and of the r ~

- 69 ~
~oundations used i~ th~ transmission line according to the iQ~entiOn will be lower than that o~ the s-tandard line.
As is known, the ratios o~ tower weights for conven-tional transmission lines depend on the ratios o~ loads applied to the towerS and are i~terrela~ed therewith as follows:

G1 , ~ (13) where: G1 ~ weight o~ tha towex with a smaller load, G2 - weight of the tower with a larger load;
N1 - mochanical load applied to the tower of :~
the weight G1;
~2 ~ mechanical load applied to the tower of the weight G2.
It follows from the foregoing that the weight of a single tower of the transmisæion ~ine accordi~g to tha inven-tion replacing four circuits of the s-tandard trans mission line will come to 2.52 o~ the weig~t of a singl0 tower o~ the lattex, but will decrease by 37% as compared with the total waight of ~our towers re~uired ~or the standard line~
~ t the same time the suspension towers of the tran~
mis~ion line according to the invention wlll have ~maller oYeral~ dimen~ions and weight as compared with the sus-pension towers of the standard lines. ~his can be illu-~ . ~" .

70 --strated by the follow.ing example. In the transmission line according to the inven-tion shown in FIG. 16 with a voltage of 500 k~ and a sur~e-impedance loading of 2600 the margi~al phases are separated ~rom each other by a distance of about 7 m, while in the standard transmi~-sion line with the same vol-tage and a surge-impsdance lo-~1 '~'/
adin~ of 900~ this distance is equal to about 24 m, i..e. 3.4 times as much. The height of the towers o~ the transmission line according to the in~ention should be also somewhat larger than with the standard transmission linea Howe~er, lightning protection o~ -the margica~ pha-ses in the latter calls for the use of -two increased height lightning protection cable posts, while in the transmission line according to the invention one lightning protection cable post ~f a smaller heigh-t is capable of ~u.rnishlng the same lightnin~ protection angle, which almost equali~es the height o~ the towers o~ ~oth lines.
There-fore, in view o~ the ~act that in the transmission line of the invention the width o~ the towers as well as the loads from the weight o~ the margina~ phases are considerably smaller as compared with the standard trans-mission line, its metal consumption and cost o~ the sus-pension towers are also much lower than with the sta~l-dard lines, particularl~ when using the suspensio~ tower~
incorporating guyed pos-t~ described hereinabove.
Dead-end, anchorg angl~ and transpositi.on towers i~
thetransmission lines accordlng to the invention are re-, ~ . , ,.~ .

latively heavier and more e~pensive than the same -tower~
of one standard transmis~ion li~e, but -they are ~ighter and cheaper as compared to the total weight and cost of these towers in all circuits o~ the standard l.~e~ to be substituted ~or one line ac~ording to the present inven-tion.
It has been said when describing ~IG. 16 tha-t the numb~r of transposition cgc`les o~ the line according to the invention is equalized with -the standard li~es b~ re-ducing the length o~ the middle phase.
Inasmuch as the towers of the transmission line according to the invention are considerably li~hter ~han with the standard transmission lines9 the foundations layed there~nder will be also much lighter and cheaper~
especially when using the base plates 2~ show~ in FIG.19.
By and large, in conformit~ with the general law o~
technology stating that an increas0 in the capacit~ and in the size o~ units tends to raise their economic ef~i~ !
cienc~ one transmission line instead of a ~ew standard transmission lines will undoubtedl~ call ~or smaller 0xpen-~itures of materials9 work power and money than the stan-dard~transmi~sion lines.
A~cording to the prelimlnar~ averaged es~imates the cost pex kilometer of the transmission line according to the inven~ion will decrease from one to three times a~
opposed to the three standard lines sub~ .ut.e.d -thereb~.
Fu~thermore, such a substi-tution of a few standard :

transmis~ion lines ~or one line according to the inven-tion provides additional savings due to a decrease in the number of switchi~g and other appara-tus ins-talled at the terminal substations. It should be also noted -that tran~-mission lines o~ the invention may emplo~ bo-th switching devices for increased curren-ts, which is cheaper than a ~ew ~uch devices for regular currents, a~d conventional switching devices connected in a one- and- a hal~ pattern -two switching devices ~or a ~ransmission line, or in an improved one-and-a~half pattern-three switching devices for a transmission line.
~ he reliability o~ an electric power supply scheme incorporating a single transmission line as compared with a few parallel transmission lines o~ the same voltage is ~enerally lower. However, judging ~rom the availab~e operating experience o~ the power systems in the U.S.~.R.
connected by a single-circui~ high-capacity tran~mission line, ~or example, the 750-kV transmission line between Moscow and ~eningrad, the opera~ional reliability of such transmission lines provided with up-to-date system auto-mation equipment is su~ficie.ntly high and ~o ~ æ has not caused an~ comple~ .bLems. ~urthermore~ the interconnec-ted power sys-tems i~corporate standb~ capacities which can be put to use ~t the time o~ repair or ~ailure o~
the high-capacity transmission line. In order to .increase the level o~ .re~iability in some cases there ma~ be built two paral~el transmission lines according to the inven-.

~ 73 ~tion~ their cost being all the same si~nificantl~ ~ower tha~ the cos-t o~ the standard transmission lines o~ the same vo~tage and total capacit~.
~ hus, when the standard transmission lines axe re-placed by the transmission line according to the inven-tion the economi¢ advantages of the latter are quite in-disputable.
In compari~g tha transmission line according -to the inv~ntion with the above-described prior art six-phase ~62-kV transmissio~ line the ~ol~owing points can be no-ted. The total section of the alumînum por-tion in each bundled phase of the six-phase line amounts to about 4900 mm , i.e. ~ice as much as opposed to the 500 kV transmis~
~ion ~ine of the invention with 10 subconductors having the total section o~ the aluminum portion equal to 240mm2, from which it follows that subsequent to matchi~g the voltages the power transmitted per 1 mm2 of the subcon--ductor sec~ion of the line according to the invention will amount to 1.08 th~kwt/mm2, and that of the above six-phase line to about 0.68 5h~kwt/mm2~ i.e. 60% ~ess~
Since the transmission line according to the invention is a three-phase on~ ~e step-up and step-doum substation~
in such a ~ine emplo~ conventional automatic circuit transformers with a phase displacement o~ 120~ electric degrees, whi~e the si~-phase transmission line re~uires the use o~ much more expensive transformers applicable . .
- ` ' ' ' ` ' ,. ' , ' ." ' ' ,, - ' ' ,, ` . `, . ` , -`: `, 6~6 -- 7~ ~
in rectifying t~chnique~ ~hus, the transmission line according to the invention is economicall~ more a~an-tageous in comparison with the si~-phase transmission line.
Other important advan~ages o~ the transmission line manifest themselves in relation to the ovexall system. On a number of occasions the transmission li.ne according to the invention of a fairly low voltage level~ when the required surge-impeda~ce loading i8 ass~red, may replace the transmissio~ lines o~ higher voltage LeveLs, this replacemen~ allowing to ob-tain an increase on the or~r of one to three levels~ Despite the continuous growth in the capacity of the power systems this wi~l permît to postpone the co~struction o~ the transmicsion lines o~
higher voltage ~evels. ~he following series o~ the voltage leveis are now current in the U.S.S.R~: 220-500-1150 kV
and 150-330 750 kV. ~he same or approximate voItage level series are in current use in all the countries o~ the world. In compliance with the ~oregoing, instead o~ the construction in the power system o~ the 750-~V trans~is~
sion line a~ the first one there is an alternative to build a transmission line according to the in~ention o~
the sa~e surge-impeda~ce loading but with a voltage o~
330 kV~ With the ~ame surge~impedanGe loading in~tead o~
the standard 500 or 1500-kV transmission line~ there c~
be respectively used the 120 and 500-kV transmission li-nes according to the invention.

:

Under on~ o~ the proaects it is envisaged to build in the U~S.S.~. A si~g~e~ircui~ three~phass transmission line standard in design and parameters intended for a Voltage o~ 1150 kV and transmitt.al o~ 4 mln~k~t at a dis-ta~ce o~ about 1100 km~ the li~e bei~g pxovidea with a single intermediate substation o~ 1150/500 kV. The estima-tes perfo~med ha~e reYealed -that in this case it is more economical to construct the 500-kV single-circuit trans-mission line according to the invention. Although the 500-kV transmissio~ line proves to be somewhat more e~-pensive and the level oP cos-tly power losses are more ta~gible with such a line, the cosb of three substations ~or 500 kV is considerably lower than the cost of three substation~ for 1150/5Q0 kV. As a result~ the entire trans-mission line according to the invention is more economi-cal not only in ter~s o~ capital investments, but also in terms o~ the economic e~icie~c~ crîterion used in the U.S.S.R. taking înto consideration both capital investmen~
and annual expendi-tures, namel~ by a minimum "reduced" or "d~sign" expendltures R:
R _ E + 0 15 C 7 (14) where: E - Pnnual expendit~res according to the alter~ative design comprising the cost o~ power losses and depreciation assign atio~s in relation to the CQSt of the -tra-~3mission line prop~r and sQbstation~;
C - ¢apital investm~n-t~ accord~g to ~he a~-ter~ati~e deæign.

, ' ' - \

~ 76 -In those cases when because o~ power considerations thare is a possibilit~ ~or building a lower vol-tage trans~
mission line out o~ the voltage scale applicable in the U~S.S.R. (150~20-330-500~750~1150) the construc~ion of the tr~nsmission line according to the in~ention inste-ad of -the standard tra~smission line o~ the following higher voltage level is almost always ~ore advan-tageous i~ the length o~ the traPsmission line corresponds to it~ voltage level, these ad~antages bei~g the more appre-ciable the larger the power transmitted by the transmis-sion line~
In some cases a newly constructed transmission li~e interconnecting two power s~stems should normall~ operate in the conditions of transmitting smal~er power levels than its actual surge-i~peda~ce loading and the surge~impe-dance loading of this line is put to us~ whenevex thQ
receiving power system underg~oes emergency power loss.
Under such emergency conditions lasting a short period o~
time the subconductors of the transmi~sion line ma~ be allowed to pass higher current ~alues than those deter-mined b~ the economic-optimum current density. These ca-ses are ~avorab~e ~or the application o~ th~ transmi~-sion line accoxdi~g to the in~ention.
As it was alread~ noted ear~ier, -the single-circuît three-phase overhead electric power transmission line accordi~g to the inven~io~ removes the limitatio~s re-garding the power levels transmitted, which have been ': '' ~ ` ' . - . .

~ 77 heretofore considered unavoidable for alternating current~
~herefore, in a variety of cases such transmission lines can be used instead of direct-curre~t high~ol-tage trans-mission lines. It is also taken i~to account -that the width o~ the right-o~w~y route required ~or the trans-mission line according to the invention does no-t a~d sometimes is smaller than the width of the right-of way route required for the overhead direct current tran~mis-sion lines.
In a number o~ cases the transmis~ion line ac~ording to the inventio~ al~o permits to si~plify crossing o~er wat~r spaces since the manufacture o~ high crossing towers o~ such a li~e is cheaper.
As it was already montioned, the width of the right--of-way route of the transmission line according to the invention is co~siderably smaller -than with the standard transmission lin~s~ If at that the tra~smission line according to the inventio~ sbhstitutes a few circuits of the standard transmission ~ines o~ the ~ame surge~impedance loading and voltage, the width o~ the right-o~-wag route of the transmission line according to the i~sntion will d~crease from 4 to 10 times as compared with the total width of the right-of-wa~ route of all the circuits of the standard transmission lina~ ~his enables to decrease considerably the area required ~ox the transmission line.
In the countries where the cost o~ larld plots ~or 6-~

transmission line rou-~ing is of paramoun-t importance such a cost being sometimes comparable with the cost o~ the transmission line itself, the use o~ transmission lines according to the invention is especially advantageous and desirable allowing to ok~ain substantial savings. Whenever the width o~ the route is restricted due to certain con-ditions, the use of the transmission line according to the invention may prove to be the only acceptable engi-neering alternative.
~ he transmission line according to the invention abates si~ificantly its ecologica~ in~luence usuall~y exe~
rted by the l~nes o~ e~trahigh a~d ultrahigh voltages.
Such in~uence ma~iIes~ itself in the increased electric gradient under the transmis~ion line ¢reating thereunder an area o~ discom~ort both for human~ and for animalb. From this viewpoi~t the propitious qualities o~ the transmis~
sion line according to the invention become readily e~i-dent in three aæpects~
~ irstly, the electric ~ield gradient under the line is maintained at a small permissible level, ~or exampl2, ~or the 5OO-~V t~an~mission line with a vertical arrange-ment o~ the bundled phases the electric ~radient under the line at h~man height level does not e~ceed ~ kV/m~
~he electric gradient at the subconductors is limited b~
the permis~i~le value o~ 21.1 kV/cm (active ~alue)~
while the corona loss amounts to 1~ kwtfmm, which e~sureæ
onl~ admissible radio i~terference and noise levelæ.

Secondly, a decrease in the width of the route redu-ces drastically the area of ~ha~ por-tio~ thereof in which the electric gradient under the subconductors shows its maximum value. This area i~ restricted by a narrow portion i~ the middle o~ the line span, for exa~ple, having a width of 7 m, which in the last resort can be protected b~ wire ropes on light supports or enc~osed.
~ hirdly, a decrease in the vo~tage level; for e~am~
ple, ~rom 1150 kV to 750 k~ or even lower to 500 kV7 re~
sults in a ~witchover from the extrahigh or ultrahi~h ~oltage transmis~ion line to the high vo~-tage ~ran~mi~
sion line displaying ~onsiderab~y lesser eco~ogical in-fluence and causing no problems.
Finallyg it should be emphasised o~ce again th~t the single-circuit three~phase overhead e~ectric power transmission li~e o~ the bund~ed-phase type according to the invention, in which an approximately uniform field is established over the entire extent of the interphase gaps, enables to bring the bundled pha~es together a~ t~le closest possible distance~ which resulks in the provision of the overhead transmission lines u~rivalled for thcir &ompactnes~ and power transmission capacitg.

Claims (20)

1. THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
   PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
   
   l. A single-circuit three-phase overhead electric power transmission line of the bundled-phase type comprising:
   three bundled phases wherein the adjacent bundled phases in the cross-section of the transmission line, at least over the major extent of the length of these phases, are spaced equidistantly, a plurality of subconductors constitut-ing said bundled phases and positioned in bundled phases in such a manner that they in one or more phases, are arranged at different distances from each other so that electric charges of the subconductors are equal whereby in con-junction with said respective arrangement of said bundled phases an electric field in the entire extent of the interphase gaps is approximately uniform, said electric field being liable to an electric breakdown upon occurrence of overvoltages in the transmission line in excess of those permissible proceeding in streamer form only, metallic members in said bundled-phases defining configurations of said bundled phases in the cross sections of the trans-mission line and securing said subconductors of said bun-dled phases at the required distance from each other, towers of the transmission line having their structural members disposed outside the space occupied by said bundled phases and air gaps therebetween, insulators suspending said bundled phases from said tower assemblies
2. 2. A sinyle-circuit three-phase overhead electric power transmission line according to claim l, wherein said spacing between the said adjacent bundled phases is such that the electric gradient between the same at an operating voltage ranges from 1.65 kV/cm with a maximum overvoltaye multiplicity factor of the transmission line, to 3.15 ky/cm with a minimum overvoltage multiplicity factor of the transmission line.
3. 3. A single-circut three-phase overhead electric power transmission line according to claim 1, wherein all of said configurations of said bundled phases are closed.
4. 4. A single-circuit three-phase overhead electric power transmission line according to claim 3, wherein said subconductors, at least in one exterior of said bundled phases, are separated from each other in the lower half of the configuration of this phase by a smaller distance than in the upper half of the configuration of the same phase.
5. 5. A single-circuit three-phase overhead electric power transmission line according to claim 3, wherein said configurations of said bundled phases represent circles ar-ranged concentrically with respect to each other.
6. 6. A single-circuit three-phase overhead electric power transmission line according to claim 5, wherein said subconductors of one of said bundled phases are equally divided into two separate semiphases, the configuration of each of said separate semiphases representing in the cross section of the transmission line a circle disposed inside the circle arranging thereabout in the cross section of the transmission line said subconductors of one of the two other said bundled phases.
7. 7. A single-circuit three-phase overhead electric power transmission line according to claim 1, wherein one of said configurations of said bundled phases has a closed design, the rest having an open design and embrac-ing the first said configuration.
8. 8. A single-circuit three-phase overhead electric power transmission line according to claim 7, wherein said subconductors, at least in one exterior of said bundled phases with an open configuration are separated from each other in the middle portion of this. configuration by a smaller distance than in the marginal portions of the same configurations.
9. 9. A single-circuit three-phase overhead electric power transmission line according to claim 7, wherein said closed configuration of one of said bundled phases repre-sents an oval, said open configurations of said bundled phases representing curves having -their convex portions turned downwards.
10. 10. A single-circuit three-phase overhead electric power transmission line according to claim 1, wherein all of said configurations of said bundled phases have an open design.
11. 11. A single-circuit three-phase overhead electric power transmission line according to claim 10, wherein said subconductors of said bundled phases are separated from each other in the middle portions of the aforesaid configurations by a larger distance than in the marginal portions of the same configurations.
12. 12. A single-circuit three-phase overhead electric power transmission line according to claim 10 or 11, wherein all said bundled phases assume the form of curves having their convex portions turned downwards.
13. 13. A single-circuit three-phase overhead electric power transmission line according to claim 10, wherein said configurations of said bundled phases represent substantially vertically arranged lines, the terminal portions in the con-figurations of the marginal of said bundled phases being bent outwardly with. respect to the configurations of the middle bundled phase and the terminal portions of said configuration of the middle bundled phase being adapted to carry on both sides from the lines of this configuration one subconductor of said bundled phase.
14. 14. A single-cicuit three-phase overhead electric power transmission line according to claim 10, wherein all said configurations of said bundled phases assume substantially the form of straight lines.
15. 15. A single-circuit three-phase overhead electric power transmission line according to claim 14, wherein said configurations of said bundled phases assume the form of straight lines arranged horizontally.
16. 16. A single-circuit three-phase overhead electric power transmission line according to claim 14, wherein said configurations of said bundled phases assume the form of straight lines arranged vertically.
17. 17. A single-circuit three-phase overhead electric power transmission line according to claim 13, 14 or 15, wherein said configuration of said middle bundled phase is of a smaller length than said configurations of said marginal bundled phases.
18. 18. A single-circuit three-phase overhead electric power transmission line according to claim 13, 14 or 15, wherein said towers are provided with a lower transverse member having the lower terminal portions of said bundled phases secured thereto by means of additional insulators.
19. 19. A single-circuit three-phase overhead electric power transmission line according to claim 5, wherein said towers comprise two posts with their tower extre-mities coverging at one point, a base having its upper portion hinged to said lower extremities of said posts at said point of their convergence, three inclined posts of said base diverging in plan from said hinged joint at an angle of 120°, base plates supporting said inclined posts of said base, 8 first flexible coupling for connect-ing the upper extremities Or said posts with their lower extremities converging at the base, and a second flexible coupling for connecting said upper extremities of said posts with their lower extremities converging at said base to the lower extremities of said inclined posts of said base, as well as for interconnecting the latter, said second flexible coupling being passed 50 as to per-mit being pulled into a state of tension from one point.
20. 20. A single-circuit three-phase overhead electric power transmission line according to Claims 5 or 9. com-prising a dead-end tower having three portal portions connected by rigid couplings and arranged in series one after the other along the axis of the transmission line, and horizontal metallic members suspended from each of said portal portions to each of which are brought out said subconductors of one of said bundled phases follow-ing a specified order, this order being such that to said horizontal member of said portal portion disposed first from the span Or the transmission line are brought out said subconductors of the exterior of said bundled phases, while to said horizontal member of said portal portion disposed last from the span of the transmission line are brought out said subconductors of the interior of said bundled phases