HIGH VOLTAGE DISTRIBUTION LINES, WHICH ARE GOING THROUGH CITIES

A. L. Ivanovski , A. I. Repin.

Siberian Power Research Institute, Russia

SUMMARY

Nobody had paid attention till nowadays on suchproblems like influence of High Voltage Lines(HVL) on views of cities. HVL have also aninfluence on people’s visions cities. Unfortunately,this problem is taken place in any big city, whichhas Power plant, or substations. HVL, whichsituated in cities (usually 35-220 kV) areabsolutely alike HVL placed where people don’tlive at all. Usually, this HVL consist typical steelor concrete poles. There construction form ismade only for one thing – to carry links withelectricity carefully. Even though this is veryimportant, but it is not enough for HVL in cities.Constructions of this pole are not only veryunpleasant to see, but make a city to look like aplant. In the same time it is necessary tomaximize the electro-secure of HVL, which aresituated in living districts. The moderndevelopment of line's builder demanding extrarequirements for wire, insulators, poles andfoundations. Now, more useful and popularbecoming insulated wires, composite insulators,

V-type insulator strings, minimizing windinfluence of air gaps and making more narrowline's corridor. Now more attention has been paidon minimizing of electromagnetic pollution inenvironment from HVL. Progressive modernarchitecture, which is demanding high-level viewof city, has a necessary of creation and buildingsteel poles HVL, which will have high architecturestandards. So-called city-type poles will have nottraditional forms, unusual design and of course itwill good influence on people view of cities.Also extra visual effect can be given with differentkind of commercials on the poles, this designerdecisions should be suit the architecture of thecity.

Authors of this article have done first steps increation of complex requirements for new city-type of HVL. They have been working ondesigner's new thoughts and decisions on city-type poles, insulators strings phase of wires andother elements of line 35-220 kV.

HIGH VOLTAGE DISTRIBUTION LINES, WHICH ARE GOING THROUGH CITIES

A. L. Ivanovski, A. I. Repin.

Siberian Power Research Institute, Russia

Until now the issue of negative effects that urbanpower lines have on the appearance of cities andtheir citizens hasn’t been raised. However, thisproblem is very typical of any big city with aPower Plant or a Substation. High Voltage Lines(usually 35-220 kV), which are situated in areasof high population density (so called "urbanlines") aren’t different from those in areas of lowpopulation or uninhabited areas, this power linesare supported by either standardized, steel orreinforced concrete poles. Their construction formhas but one aim: to care wires securely. Thus,guaranteeing uninterrupted functioning of powerlines. This condition is necessary, but insufficientfor urban power lines. Construction forms ofpower line pole do not meet even minimumesthetic requirements. Thus making city districtslook like construction sites. In the moderncondition of progressing development of urbanarchitecture and heightened requirements ofappearance of densely populated areas, thenecessity of solving this problem is very topical.Though, we should notice that with all theimportance of the problem, it is not alone andrepresents just a part of the problem to beconsidered forming steel power lines poles. Asstated earlier, high voltage power lines in ourcountry is based on the usage of standardizedline poles. The standardization of power linepoles has significant advantages: chance tomass-produce, worked-out processes ofinstallation, and exploitation. However, it also hasdisadvantages. For instance, it restrained thedevelopment of structural forms of power linepoles that of new installation technologies. It alsodidn’t account for climatic and geographicvariations of passing courses of high voltagepower lines, etc. So the conception of formationof steel poles – a basis for their development andconstruction – appeared. Briefly the conceptioncan be characterized as a code of generalprincipals, on the base of which TechnicalConditions of projecting of steel High VoltagePower line poles should be developed. In thebase of the conception the analysis andclassification of quiet a big number of factors lie.These factors can influence the constructionalform of poles. They were named as influencefactors and were classified on definite base,forming different groups. In one of such groups,named as “regional”, the requirements for urbanHigh Voltage Power Lines are settled.

Complex of the main requirements, which thepoles of high architectural view must meet, canbe as follows.

Aesthetic requirements (architectural view).

The determinative parameter for the poles of thiskind from the point of visual influence on thepeople is of course their form and color. But weshould pay attention to the fact that form shouldnot be at variance with safety and reliability of thelines, going through the populated areas. Theform should attract people’s attention by itssingularity and even eccentricity. But for all thatthe economical requirements for urban highvoltage lines don’t have primary importance. Asfor the color of each pole, which can be verydifferent, it should underline the form, be inharmony with it and so serve to attract people’sattention. The pole should be open-work,not massive. So the preference should be givento through constructions or at least combined.Hence constructive elements with symmetricalsection, which ratio between max. cross size andmin. cross size is one, should be used. The idealsection meeting this requirement is tubular.Without gusset coupling of construction elementsor at least ball (or similar) central fixing ispreferable.“Aesthetic optimization” of the main sizes of theline: determination of the bay size and thereforefrequency of poles allocation, determination ofpoles height and width of their foundation, on thebase of aesthetic concept, linked with thearchitectural composition.

Minimization of poles occupied urban space.

To satisfy the requirements of minimization of thetaken urban territory, it is necessary to use thespecial poles, for example tower type. At thesame time this requirement dictates the extensionof the distance between poles (this as wellcoordinates with electrical requirements).Diminution of phase to phase distances thuslessening of the occupied territory is possible onlyin case of using of the fixed wire suspension –anchor, V -type insulators strings, pin orsupporting insulators, phase to phase crosspiece, etc.

"Urban type” lines should have increasedoperational safety, electro safety, electromagneticcompatibility.

To use closed cut metal profile persistent to themechanical damage and corrosion as poleselements.To use polymer insulators instead glass andporcelain. Quite a great experience of usage ofthe polymer insulation (more than 20 years)showed their high reliability. Convenience of theirinstallation and exploitation makes it possible tomention them as preferable insulation for urbanHVL.To use steel of higher strength – that gives theopportunity to make the pole more open - workand increase the corrosion resistance.Constructive forms of central coupling of poles,exploitable in low temperatures, that is typical, forexample, for Russia), should have high level ofresistance to brittle failure of steel. The danger ofbrittle failure is that it is such a type of failurewhich has too low electro-capacity and ischaracterized by indefinite low level of breakingvoltage, lower than that of steel.

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Fig. 1."Urban type" pole.

Fig. 2

"Urban type" pole withpipe section.

Investigation of the questions of electromagneticcompatibility of HVL of “urban type” makes thelevel of interference from phase wire andconnective reinforcement of the line lower.Economical current density is decreased till 0.7-0.8 A/ mm2, at the same time the radius of wireand metallic elements of work potential isincreased. But the substantial increase of thesurface of the current-carrying parts can causethe local heterogeneity and local corona. As aresult the use of insulated or partly insulatedwires and armature, colored light tones, is verypromising.

The authors of the article have studied a numberof constructive types of “urban” HVL. As anexample on the Fig. 1, 2 pole, the construction ofwhich is based on the usage in a role of unitedcross-arm – transparent special configuration –cellular ball, which has the high level ofarchitectural view is shown. At the same time thestock in one of the variants of pole (Fig. 1) ismade by through, in the second (Fig.2) – bycontinuous pipe section. The “urban type” poles,which conception of formation was describedabove, can be used for re-equipment exploitableHVL with practically spend resources, and alsofor new building sites on the populated territories.