L1ITest dient, G,, obtained from Peek's relation-ea vi le is -)Nltitu e c nvl est ship for polished tubes at sea level. It isimportant to note that the critical gra-Project-S ingle-C onductor Tests dient, G,, increases as the diameterdccreases. The projected, critical gradientvalues, "G,," vary in this same manner

L. M. ROBERTSON J. C. SMITH as seen from the ratio between theseFELLOW AIEE values (Go/Gc)-

The equivalent 3-phase voltages shownW. E. PAKALA J. E. O'NEIL in Table I were calculated using a line

FELLOW AIEE MEMBER AIEE design identical to the Leadville TestLine with a 3-phase circuit using the sameconductor diameter as the one under

Summary: The corona loss and radio that time, tests of corona loss and RI test. The gradient on the center conduc-influence (RI) levels from 2 years' testing level have been made on single 0.92-inch, tor for the 3-phase calculation is identicalon conductors designed to bracket the level a n 1ade on SR0 steelh to the projected critical gradient, G,, for230-kv operating range at high altitudes 1.4-inch, and 1.65-inch ACSR (steel- the voltages shown.indicates smaller conductors than originally reinforced aluminum cable) conductors. Figs. 3, 4, and 5 show corona loss in-estimated will perform adequately. The 1.65-inch conductor remained as aResults of high-frequency tests give values control conductor, and the other twofor radiation and attenuation at fre-quencies in the 10- to 200-inc (megacycles) brce th 23-yoraig an. 7 1range. Mechanical observations have These tests have continued from 1960 toshown conductor oscillations which are the present time to obtain high-altitudeproduced by heavy corona and damp data ontheseconductorsizesfor selecting s - - - - Lconductor conditions. *

a conductor that wil give adequate per- Iformance from an RI and corona loss

THE LEADVILLE Test Facility, con- standpoint. 15 - --ceived in 1952, was constructed to 15

obtain direct experience in the corona loss Tests and Instrumentationand RI levels of extra-high-voltage (EHV)lines at high altitudes. The 10,500-foot The tests reported here were conducted 14; 4 81 905altitude of the test location, with an aver- during seven test periods in which data PROBABLITY DISTRI8UITONage barometric pressure of 20.5 inch Hg were logged manually by test personnel.(mercury) (sea level 29.92 inches) was Twenty-seven fair-weather tests, where Fi 1. Probbility distribution of d1b,ideal for such a program.1 2 the voltage was varied and corona loss 1.65-inch-dlmet r ACSR conductor, 1960wThe Leadville EHV Test Project has and RI recorded, have been made since February 1962

been in operation since November 1956. July 1960. Four or five similar foulA great amount of data has been ob- weather tests have been made. Thetained, analyzed, and reported.3'4.5 This instrumentation used for these tests wasearlier information dealt primarily with identical to that reported previously.'conductors selected to bracket 345-kv A continuous data logging system was Al )FIOALO^sSoperating levels at high altitude. With used to monitor the long-term operationthe selection of a 230-ky design level for of the test facility. This system wasseveral lines that are being built in the changed in early 1961 from continuous _ _Rocky Mountain area, the Leadville Test pen chart recorders to a multipoint sam- _ 6a, 14'co 7Facility was changed, after sufficient 345 pling-type recorder in order to improve / /kv experience, to evaluate smaller con- the method of recording data. co

wj 20.0ductors for operation at 230 kv. This -tchange was made in July 1960. Since Corona Loss

The comparison of single conductors lPaper 62-1096, recommended by the AIEE Trans- T c omission and Distribution Committee and approved has been made using the data obtained co -__by the AIEE Technical Operations Department sicfor presentation at the AIEE Summer General July 1960. To insure that data X|Meeting, Denver, Colo., June 17-22, 1962. Manu- collected could be analyzed as normally 9 /script submitted March 21, 1962; made available distributed information, checks were madefor printing May 1, 1962. atrl differentle corona

Z

L. M. RoBPRTSON and J. C. SRlTHs are with the at several different levels of corona loss.Public Service Company of Colorado, Denver, A sample of this information is shown inl/Colo., and W. E. PAKLA and J. E. O'Nsn, are 20 0with Westinghouse Electric Corporation, East Fig. 1. The data are sufficiently close to /lPittsburgh, Pa. normal distribution so that normal dis- 1.f0 v>The authors wish to ackrnowledge the support tribution techniques can be used. 4 -__ /X __ < co oand help of the many people, both in their owrn >.companies and the companies asoited with the The average values of fair weather loss 2 Z</-it2--test program who help to carry out successfully for each conductor have been plotted in o,-- IS IS XBparticipating ln this project include Public Service Fig. 2. Also shown are the projected 9"Company of Colorado; Westinghouse Electric..Corporation; Aluminum Company of America; values of critical gradienlt, G,, for each con- Fig. 2. Average fan eather corona loswOhio Brass Company; American Bridge Division ductor. Table I gives this value and values for conductors tested at eadville froasof United States Steel Corporation; HughesBros., Inc.; and Malleable Iron Fittings Company. shows its relationship to the critical gra- July 1960 to Feba,y 1962

FEBRUARY 1963 Robertson, Smith, Pakala, O'Neil-Leadville EHV Test Project A3

500 _r_- 77 formation taken on each conductor. Table I'I 1/ / The fair weather data are shown with

limits of two stancard deviations which Con- Equivalentductor, 3-Phase, Projected Go. Ratio.includes 95% of the data. Fair weather Inhe Kv Go. RMS Ro CS G/oGe

I|1 /1 f corona loss varies over a wide range for/i any particular gradient. For a mean 0.92. 216.5. 17.05. 26.9. ....0.634IIIII I >/111 L I/ value of 0.2 kw/phase mile, corona losses 1.40.. 302.0. 1.7 25. 0.6

LOHTRA IN Ivaried from zero to 1.5 kw/phase mile. 1_65______440_....._15_2_____2___...._0_5_200 - . . . _ Thus, to predict line performance, a

OLE I ) l / r statistical assessment of a considerableMEAN number of tests must be made. Augst 1960 to Febr 1962. The

-|l l/ ] / Z I l l Foul weather data, limited to individual variation, however, between the three toz o0.0 - - - _ _ curves, are plotted on these same figures. five voltage runs taken during each testif | The variability of rain and snow condi- series was not nearly as large. Fig. 6

- - AND-iSTO. tions, in intensity and area of coverage, shows the average fair weather RI valueso 5.0 - t- / / _ I makes statistical analysis of these limited obtained under the conductors for the

data impossible. It can be seen that seven test series.§2.0 t_ - - - - - losses can be high, and quite variable

for these conditions. MEASUREMENTS AT 200 FEET1.0- - - - --

Measurements were made at 203 feet.4 . . . . . .Radio Influence west from the center phase of the line and.2 -;1 - - - - - PROJECTaED , M at 200 feet east from the 1.4-inch-diameterO L P

. MEASUREMIENTS UNDIER CONDUCTOR13 14 1U5 1E6 17 C U 19 conductor. These measurements wereGiRADIENT IN KVrms/CM The RI field was measured at each test always made at the same time as the300 32 35 I375 400 voltage under each conductor at three measurements made under the conductorEQUIVALENT THREE PH1ASE VOLTAGE

locations 50 feet apart along the line with and shown in Fig. 6. The averages of allFig. 3. Statistical distribution of fair weather the 1-meter vertical antenna. These readings made at 203 feet are shown incorona los on the 1.65-inch ACSR con- measurements can be used to compare the Fig. 7. The values were all corrected asductor, July 1960-February 1962. Foul three single conductors since readings on the square of the diagonal distance to theweather curves are from Individual tests the conductors were taken only 3 to 5 conductors from the actual measurementThe equivalent 3-phase voltage given Is for minutes apart. There was considerable locations, which were east and west of the

28-foot horizontal spacing variation in the RI values for all conduc- line.tors over the complete test period from The RI level with respect to the cal-

50.0 ~~-- Fig. 4 (left). 50.0.Statistical distri- /.'|'~-R^"NW4f// bution of fair

A-F1Lf IIIII weather corona .

/ l~~~~onon the 0.92.Inch ACSR con- /

-- ~~~~~~~ductor,, July_1/ 1-1960.- February _ - -

- - 1962. F oulIweather curves. /

I I/ _//ISPRI JEC&E0 Go | L eare from Indi- -

vidual tes1. The16 7VARIABLE /

N /VLm/ HT equivalent 3.. wINTERMITTENTsi~~~~~~ow,SNOW ~~~~~~~~~~~~) LIGHT SNO

I?0 /25 250I275 ph^se voltage 250 m 300 325 350tae

LIGHT/ENT

'\4REE MHASEVOLTANE given Is for 28-

H EAVY1940 Robertson, Smith, Pakala, O'Ceil-Le EHV Test Projecspacing FER.A 19~J-PN0-2STD. Fig. 5 (right). cn

RAIN ---- DEVIATIONS Statistical distri- \A/R/A"~~~~ /' ~~~~~~bution of fair 050NO5.0-7- - ~~~~~~~~~~~~~weathercorona g --/ ~~~~~~~~~~~~~~~losson the U ND T3

1 r--r ~ '- ~- 1---rrFig. 9. It can be seen that the fields

strength at 200 feet 'is very nearly 60 db _1.4'D-To___ below the conducted voltage. At 200 1.6TDIA 92' DIA.

feet the critical or RI start gradients in , | .EDIA|O~~~~2M4j0AI-l s/ 4,/I4;SD1 IElINA.I a snowstorm is 9 kv/cm (per cenlt'imeteir). t-I !___ ACSRJACSI ACSR ai pr~~

f > l1/ 2 L 9; 12 ~~~0- TO 1,(000-Mc MEASUREMENTS X20 < ||||2

E F ||t /1 / 2 ~~Measurements were made with tuned 1 g

0911A1CA 6DI nwsom ,0--.

5 4 _ / / / dipole antenna and Stoddart meters at It 1 / / frequencies from 20 to 1,000 mc. The a

0.92-inch- and the 1.65-inch-diameter con- 2 4 6 8 ) 12 14 6 20 2Z 24 26 21GRtADIENT IN KV,,,/CM

j ~ _ _._ ductors were tested with a gradient ofL20 -_ | . . ~~~17.5 kv/cm. Some radiation measure- 17.5,ky/cm. Some radiation measure- Fig. S. Average Fair weather radio inRuence

- ments were also made at 52.2 mc with levelsas a function of surface voltage gradient,a signal generator connected to the 1.65- 200 feet from the conducto, for the seveno L1 | 12 inch conductor at Tower 3. series of test, August 1960-February 1962

SO 100 1SO 200 250S 30 3S0-EQUIVALENT 3¢) KV Frequency Spectra

Fig. 6. Average fair weather radio inRuence The RI measurements were made with heights and reflections from the groundlevels under the conductor for seven series of a tuned dipole 12 feet above earth. The plane will occur. It is not intended

tests, August 1960-February 1962 dipole was rotated in a horizontal plane to that the measurements described areobtain maximum and minimum values of sufficient for exact evaluations. Theythe field. The spectra are shown for the were made to show what variations can

culated gradient on the conductors is 0.92 conductors in Figs. 10 and 11. The occur on a line in corona.shown in Fig. 8. For the same gradient instruments were scanned up to 1,000 mc. Laer Profikthere is a 6-db (decibel) difference im the No corona noise could be measured orRI level. The 1.4-inch-diameter ex- heard in the headphone above 160 mc. Lateral profiles were obtained with thepanded conductor has the highest RI level In general, as can be seen from the 1.65-inch-diameter conductor energizedfor the same gradient. The earlier tests antenna orientation angle given on the first with 60-cps (cycles per second) volt-on 2-bundle 1.4-inch conductor gave curves, the miimum readings were ob- age, and later with a signal generator atsimilar results when compared to the 1.65- taied with the dipole parallel to the con- 52.2 mc. These laterals are shown in Fig.inch single conductor and the 2-bundle ductor and the maximum readings were 12. There are no large decreases in0.92-inch conductor (see Fig. 16 of obtained with the dipole at right angles to measured RI field with distance as isreference 3). the conductor and in a horizontal plane. found at lower frequencies. These lat-

The 0.92-inch-diameter conductormeas- erals seem to indicate that the princialCONDUCTED VOLTAGE MEASUREMENT urements were made between Tower 4 and sources are far enough away to makeConducted voltage measurements were Tower 5 (Fig. 10) and also opposite the lateral distance change insignificant.

made with the 600-ohm NEMA (National Tower 5 (Fig. 11). The antenna orienta-Electrical Manufacturer Association) test tion angle for maximum and minimum Polar Pattern Under Conductorcircuit on the 1.4-inch-diameter conductor was about the same when opposite the With the signal generator connected toduring a snowstorm; at the same time, tower as when opposite mid-span. the 1.65-inch-diameter conductor atRI measurements were made with the in- Measurements at these high frequencies Tower 3, and with the dipole under thisstrument directly under the 1.4-inch- vary considerably with antenna location conductor at mid-span between Towers 4conductor and at 200 feet from the 1.4- and antenna height because the wave- and 5, the polar pattern shown on Fig. 13inch conductor. The data are shown in lengths are less than line and antenna was obtained. Here again the antenna

1.4" 5IA 1651 2IA /0 30T°

50~~ ~ ~~QIVLN (pKVON+

0.92-' DIA. ACS ACSR 110 - / MACSR cnutdb ABOVE I sV

B 40 6 9U)

- &*bBOVE00 UN-DE~~~~~~~~~~~~~~~~~10RLUNE

I19303 - 0-

rso

20

100 I~-~Tj~ V IT Fis. 10. The very-high. in contact with the poles bonded andtfrequency spectrum of the grounded, giving the added impulse char-

60 g - ~ - radiated field measured at the acteristics of the timber arms.a40 > 1\ _/T4 k Z. T5. center of the pan. Line co- The conductor surface has not changed

z \ A _/- 6t, < - rona was highly audible sufficiently to indicate any discoloration,-0 - | directly to the ear, and corona

2D 12'A-Se~.~M noise could be detected in o aig odtos*0l \ ^ the headphones up to 160 Galloping of conductors has been ob-1 r s\a/\@* ...-| \ mCI 1,100 microvolts per served with amplitudes up to 18 inches

meter, quasipeak, was meas- and wave lengths up to 150 feet. This\^,,8 _- at 1.035 mc with the condition existed when the conductor

X 6 W 4 FR \48- < ~~~~~vertical anteinn at this wasincoronaandwaswet. Theseoscill-t 4 L I| I 1 '°'location tions were observed with practically

4 r - no wind, and disappeared when voltage3 -+DIt LE ^ ^ _Iwas reduced to a point where corona was

_2 _ - - \___-oX*f^ _ _ __ eliminated or the conductor dried out.aF ll¢; a This phenomenon was not observed on

~ :' ~ the bundle conductors. However, in high0 2 0 3 0 SD 6 0 -2-20cross-wind conditions, travelling waves

MEA-CYa.ES/SIC and horizontal oscillations between sub-conductors of the bundle were observed.

IO- r- rT

Q__ __ _ __ __ _ Conclusions

r _ 1. There is no indication visually or elec-_

40 092_ T46 trically of "aging" after 6 years of testing.

- 30 __o 2. Referring to the comparative levels ofTUfDDIPOLE \t-r - RI and corona loss, it is indicated that the

u 20 H RI level rather than corona loss is the deter-zf |- 1\ FAIR WEATHER-AIG2,J96I mining factor in selecting conductor sizes

for Leadville conditions.K10 F\ -- Fig. 11. The very-high-frequen. 3. The corona and RI data presented showjd8 t 14mCyspectrum of the radiated that the diameter of single conductors can

-o - _s>\ \l t_" field measured at the tower be reduced below those predicted by investi-I I I I on the 0.92-inch-diameter gators prior to the Leadville Tests.

3- 4 t ,.>^ X M ACSR conductor during fair 4. Both corona loss and RI data show thatweather at 153 kv/ground smaller diameter conductors may be op-(17.5 kv/cm surface voltage erated at higher gradients than larger ones.

gradient, and 230 kv equiva- 5. Sawed timber fixtures were satisfactoryi3 l ,lZb t d lent 3-phase) through 4 years of testing with only hard-

l~~~~iI4 I11> 120 330 100 2i00 300 6*0 1000-MEGA-CYCLES/SECE 4

600

was almost exactly at right angles to the -7/conductor formaximum reading. DIPOLE 0,

200 1_| +

Mechanical Considerations

The Leadville Test Facility was de-signed to evaluate many factors of me- -cochanical design as well as test electricallydifferent conductor arrangements. The 8. I 1high altitudes, working conditions, andremote locations in the mountainous areamake ease of construction and mechanical .operation very important. The test facil- |ity used many designs and observed many ' - a

different phenomena to aid in the solution Fig. 12. Sine wave and line 2 t MIN.o 1 ito these problems. RI signals measured with a a 6 -. o i~ sThe isokeraunic level is quite high in tuned dipole at 52 and 50 ___ ____>21

the Rocky Mountains (50-60) and it is mc on the 1.65-Inch-diameter )' 1\desirable to use high impulse flashover exane ACS conductoras a function of distnce 2 I _characteristics to avoid line outages. from the center line of theThe sawvedtimber-arm fixtures used in the test line. Line RI quasipeaktest project proved satisfactory through values were taken at 225 '0 20-40 -60 8010 120-4 years of testing with only the hardware ky/ground DISTANCE IN FEET FROM (

942 Robertson, Smith, Pakala, O'Neil-Leadville EHV Test Project FEBRUARY 1963

23jgg 10 0 358 Fig. 13. Polar feld pattern ware in contact with the poles bonded and40 at 52.2 mc with the tuned grounded.320 \ >< \ \ = 6 / / < / 4° dipole directly under the 6. Because of the many uncontrolled1.65-inch-diameter expanded variables that exist on actual transmission

ACSR conductor. The lines, tests on full-scale facilities over an35 \/ antenna is 12 feet above extended period of time are required. The\/\/the earth and s horizontal Leadville Test Facility has met these re-

f\or all values of 6. The quirements and allowed the determinations8\ / ignal generator was attached of the effects of many of these variables.

aCK X g I <' a to the conductor at Tower 3290 ?O ~~~~~~~~~~~~~~~References8D?>\ 280

280 Z \XS \\ LXlJ ; 5 \ 90 so1. COLORADO HIGH-ALTITUDB CORONA TESTS,PARTS I-III, L. M. Robertson, et al. AIEE90 MICW-rS /MfTERl70 2 1Transactions, pt. IlI (Power Apparatus andSystems), vol. 76, June 1957, pp. 356-76.

X x A-/X //T \ \X\\L I _ _ 260 2. HIGH ALTITUDE CORONA AND RADIO IN-FLUENCE MECASURING INSTALLATION AT LE3ADVILLE,

110 /\2DQ< L \ \\ 79 50 COLORADO, L. M. Robertson, C. F. Wagner.2X50 X / C S L \ ; ) 110 Paper No. 405, CIGRE, Paris, France, 1958.

120 240>C / _ I \/3. LEADVILLB HIIGR ALTITUDE EXTRA-HIGH-

24C0\ / \/ / I \ \ \ / \ /N 120 VOLTAGE TEST PROJECT, PARTS I-IV, L. M.Robertson, et al. AIEE Transactions, pt. III(Power Apparatus and Systems), vol. 80, Dec.

130 K/ \S / \ \/ \ 230 1961, pp. 715-748.

1/0 X / I \ \ N \4. PHOTOS SHOW EHV-LINu NOISE SOURCES,L. M. Robertson, J. E. O'Neil. Electrical World,New York, N. Y., July 20, 1959, pp. 90-91.

140 220 5. LEADVILLE TEST PROJECT-EHV AT HIGH-220 140 ALTITUDEDS, L. M. Robertson, J. K. Dillard. West-inghouse Engineer, Pittsburgh, Pa., May 1961,......

2 518 190 200 1pp. 66-71.

Discussion It would be very helpful, in addition to the have been excluded from the fair weatherdata presented, to have a complete field data. At times some snow or rain wouldpattern of both the electric and magnetic come down after a voltage run was started.

J. J. LaForest (General Electric Compatny, vectors at various lateral points near and If weather was so variable that resultsPittsfield, Mass.): Of great interest in the far away from the line. This would involve would neither depict fair weather nor snowreporting of fair weather data on corona not only electric field measurements in a nor rain all the RI and the corona testsdischarge phenomena is a definition of the plane parallel to the earth, as was done in were stopped. Recorder data taken atset of climatic conditions that constitute a this paper, but also field plots in planes night and early in morning showed veryfair weather period. Obviously, data taken perpendicular to the earth which are parallel constant values of RI in fair weather overduring periods when rain or snow is falling and perpendicular to the line. These addi- large changes in humidity and temperature.should not be included. After periods of tional data would establish whether radia- In winter, snow and ice gather at times,precipitation, the conductor surfaces are tion is present, the extent of the induction in small amounts, on the conductors.still wet and for some time continue to field, and other useful information. However, on sunny days, these depositsbehave essentially as they did during foul disappear rapidly and the RI level decreasesweather. What period of time have the and becomes constant.authors allowed for conductor surface J. Reichman and J. R. Leslie (Hydro- From previous Leadville tests (see refer-drying after precipitation has occurred? Electric Power Commission of Ontario, ence 1 of the paper) the air density correc-The formation of dew on conductors yields Toronto, Ont., Canada): Regarding very- tion would be 0.85. Values for strandingrelatively high RI and corona loss values. high-frequency (VHF) noise measurements, factor and surface factor cannot be de-Have those periods when dew was present we would like to know the authors' opinion termined manually from Leadville tests.on the conductors been excluded from the as to the source of this noise. Our experi- The effect of the conducted voltage meas-fair weather data? ence shows that conductor corona, even uring circuit on the field strength readingsWith regard to the data shown in Table though very intense and having RI levels was checked by disconnecting coupling

I on the ratio of the measured critical greatly exceeding those quoted, does not capacitors and by short-circuiting loadinggradient to that calculated from Peek's result in measurable VHF noise. Spark-type resistance in the NEMA high-voltage RIVformula, it would appear that a stranding discharges on insulators and on non- test circuit. No change in field strengthfactor, air density correction factor, and current-carrying hardware, however, pro- readings was measured. The couplingsurface factor would account for the ratios duce interference at VHF frequencies. capacitor is located so that at 1 mc thegiven. What percentage values would the This noise does not vary directly with the electric field standing wave at capacitorauthors assign to the above factors with voltage. Have the authors any informa- location is at half magnitude. The ratioregard to these ratios? tion on the source of this VHF noise and of RIXV to RI field at 200 feet from conductor

Taking conducted voltage measurements its variation with the line voltage? Noise was measured to be 60.4 to 62 db, depend-on a line may result in undesirable line- levels, at these frequencies, become im- ing on the conductor, and the calculatedloading effects. What were the effects of portant if VHF radio is used for automatic values are 59.7 to 62.8 db. These are giventhis loading on the longitudinal profile? control and telemetering. in Table III of referencel1of the paper.Has the ratio of measured RIV to measured We agree that the measurement of theRI field at the 200-foot point been compared E and H fields near and far fro>m the lineto calculated results? L. M. Robertson, J. C. Smith, W. E. Pakala, conductors at high frequencies would giveThe measurements of the RI field in the and J. E. O'Neil: We agree with Mr. useful information. Our measurements

frequency range of 20 to 1,000 mc were LaForest that climatic conditions, dew, were quite limited. However, they dovery interesting. It would appear, from awnd wvetness of conductor surfaces affect indicate that high-frequency E field nearthe measurements with the tuned dipole, the RI level and that all of data under these the line is quite low at VHF and ultrahighthat astrong Efield component parallel to conditions should be excluded from the frequency (UHF) even with high conductorthe earth and in a plane perpendicular to fair wveather data. All data taken during gradients and with excessive audible coronathe line exists with little lateral attenuation. any precipitation, regardless of amount, from the conductors.

FEBRUARY 196,3 Robertson, Smith, Pakasla, O'Neil-Leadville EHV Test Project 943