ML20128C082
| ML20128C082 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 05/17/1985 |
| From: | Chan E NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| To: | Gallo J ISHAM, LINCOLN & BEALE |
| References | |
| CON-#285-094, CON-#285-94 OL, NUDOCS 8505280178 | |
| Download: ML20128C082 (20) | |
Text
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6, ,.IC ,, UNITED STATES j, ~ ,-: g NUCLEAR REGULATORY COMMISSION L 'j WASHINGTON, D. C. 20555
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/
May 17, 1985 @ '
00CKETED USHRC Joseph Gallo, Esq.
N'gN"CI"88'*l' '85 MAY 22 Pi:51 1120 Connecticut Avenue, N.W.
Washington, D.C. 20036 CFFICE OF SECRETAiW 00CHETING & SEFVlf' ERANCH In the Matter of COMMONWEALTH EDISON COMPANY (Braidwood Nuclear Power Station, Units 1 and 2)
Docket Nos. 50-456, 50-457 -d 6
Dear Mr. Gallo:
In response to your request enclosed please find copies of the two scientific papers referred to by Dr. Penecost in his May 16, 1985 deposition and entitled:
- 1. " Measurements of Electric and Magnetic Fields in and Around Homes Near a 500 KV Transmission Line," by R. J. Caola, Jr., D. W. Deno and V. S. W. Dymek, IEEE Transactions on Power Apparatus and Systems, Vol. PAS-102, No. 10, October 1983.
- 2. " Analysis of Electric and Magnetic Fields Measured Near TVA's 500 KV Transmission Lines" by M.'Senduala, D. W. Halson, R. C. Meyers, L. G. Akers, and B. J. Woolery, IEEE Transactions on Power Apparatus and Systems, Vol. PAS-103, No. 2, February 1984.
Sincerely,
^-- % .
p Elaine I. Chan Counsel for NRC Staff
Enclosures:
As stated cc'w/ enclosures: Service List 850528017s 850517 O PDR ADOCK 050 f Q
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IEEE Transecuous en Power Apparatus and Systems. Vol. PAS-103 No. 2. February 1984
, } ' ' ; 333 ,
AllALYSIS OF ELECTRIC AllD MAGNETIC FIEIJls MEASIEtED NEAR TVA'S 500-kV TRANSMISSION LINES ,
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liusoke Sendaula D. W. Hilson, R. C. Nyers, .
._ School of Engineering L. G. Akens, B. .I. Woolery University of Tennessee-Chattanoogs Electrical Systems Group Tennessee Valley Authority
,. ABSTRACT gested sensurement guidelfnes for the field meter .
(Electric Field Measurement Company Model 110) and a In a program sponsored by the U.S. Department of preliminary statistical analysis, the electric field Energy (DOE), the Tennessee Valley Authority (TVA) has . data were categorized as follows: i
' developed an extensive data base on electric and magne- (i) Flat terrain, at a measurement height of I a
' tic fields in the vicinity of TVA's 500-kV transmission above ground level lines. This paper summarises the grouping by categor- (ii) " Flat terrain, at a measurement height of ).5 a
~ fes, the analysis, and the documentation of the data, above ground level .
The seasured fields data are analyzed statistically as (iii) Rolling terrain, at a measurement height of I e a . function of the transmission lines' geometrical above ground. level
. parameters and topographical factors. (iv) Rolling terrain, at a messarement height of j
1.5 m above ground level These categories were further subdivided for the elec-l I. INTRODUCTION tric fields into shielded (rights-of-way bordered by trees) and unshielded subcategories. A more complete Increasing concern over the possible effects of presentation and analysis of the data is contained in electric and magnetic fields in the vicinity of ENV the TVA/ DOE 500-kV electric and magnetic fields project transmission lines has made it essential that electric final report [11]. .
utilities be able to predict accurately the magnitudes In this paper, the influence of ground cover of the fields. The objectives of the 1VA/ DOE 500-kV heights, terrain, and tree and other shielding objects. ,
electric and magnetic fields project were: on the electric fields near the transmission lines will ,
! (i) To measure, analyze, and document electric and be outlined. Statistical averages of the maximus mes- F assnetic fields . data 'in the . vicinity of TVA's suced values and values at the edge of the right-of-way 500-kV transmission lines. of the Electric field near the ground under TVA's 500-(ii) To assess the effects of the ENV transmission kV transmission lines, as functions of the geometrical .
line fields on the growth and development of parameters of the transmission lines, are presented. A selected agricultural and forest species. statistical summary of the data from each of the four ,
This paper summarizes the collection, categoriza- siajor categories is also included. The data could be
, tion, analysis, and documentation of TVA's 500-kV used by TVA and other utilities whose transmission line fields data. The assessment 'of the effects of ENV designs are similar to estimate the range of the elec-
. fields. on agricultural and forest species will be tric fields .for various terrains and ground cover reported in a subsequent paper. The data base that was heights. The possible use of the data in DOE's 60-Hz generated during this investigation consists of approx- electric fields bioeffects research is outlined in
. instely 2,700 data sets of electric and magnetic pro- [10]. The data may also be,useful in future regulatory d
- files measured at various locations on TVA's 500-kV studies [8].
transmission grid. The locations included road cross- Section II of this paper summarizes the methods of ings, agricultural areas (various crops), wooded areas, calculating and analyzing the influence of transmission
.and flat and rolling terrains. line geometry and the topography on the electric and Transmission line fields, especially those under magnetic fields. Procedures of measuring electric and ENV and UHV transeission lines, have been investigated magnetic fields are outlined in Section III. In Sec-extensively by the Electric Power Research Institute tion IV, a statistical summary of the data is given.
(EPRI) [1,2], IEEE [3], and other independent investi- Concluding remarks are found in Section V.
gators l4-10]. Various aspects of measuring, calculat-l ing, and determining both " biological" and " electrical" effects have been documented. Measurements of electric II. CALCULATION OF ELECTRIC AND MAGhTTIC FIELDS r, and magnetic fields under ENV and UHV transmission lines to date have been limited and are for selected A method for computing transmission line electric
, sites. The data gathered during this project included field over irregular . terrain [9] is used to compute
! ground cover height. . topographical descriptions, line upper bounds on the field magnitudes due to topography.
geometrical parameters, as well as the measured elec-
- tric and magnetic field magnitudes. Electric Field Analysis--Flat Terrain
- The data was measured according to the IEEE Stand-
- ard 644-1979 as outlined in [3]. Following the sus- The electric field due to ENV overhead ac trans-p , mission lines are computed assuming the following
- (i) there is no free charge; (ii) the permittivity constant t is 8.85x10 12 F/M; and (iii) phase conductors form a
~~
.- set of parallel line charges over a flat perfectly con ,
ducting earth. A detailed discussion of the calcuation 83 SM 463-7 A paper recommended and approved of electric field is given in [2]. During the data by the IEEE Transmission and Distribution Committee collection task, nominal lateral electric field pro-of the IEIE Power Engineering Society for presenta- files were computed for the flat terrain for various
- tion at the IEEE/ PES 1983 Sumer Meeting, heights and phase spacing to give the field crews a way
, Los Angeles, California, July 17-22, 1983. Manu- to check measured data that appeared questionable. If script submitted February 14, 1983; ande available no simple explanation for questionable data was found, for printing May, 19, 1983. some points on the profile were renessured.
0018-9510/84/0002 0328301.00 01984 IEEE
, , . , . =
' - l' 329 .
In order to estimate the errors that were intro- due to magnetic fields are much less than those due to dic:d into the data due' to an error in measurement of electric fields [3], a detailed analysis of the magne-line height, the influence of line height on the elec- tic fields has not been performed. . * ,
tric fields at 1 e above ground has been determined. . V _ . -1 a Th2 relationship between minimum line height and the maximum field at the ground was developed in [2]. The III. FIELDS MEASUREMENTS ,
ecpirical equation is: This section contains a brief description of TVA's 500-kV grid and a general description of the data col-E /E = (Hg/H2 )" 2.1 lection sites. Procedures of measuring electric and magnetic fields are also summarized. ,
whira En and E2 are the maximum fields for lines of f hiights H1 and Hz, respectively; and where "a" is TVA 500-kV Grid tppreximately. - 1.4 for a three phase line with flat The TVA region consists of the state of Tennessee
' spacing.
It follows from (2.1) and from calculations using and portions of six adjacent states. The western part ,
th2 "sethod of images" [3] that the maximum error in of the region area is essentially flat, while the cen-th2 naximum electric field (at 1 e above ground due to tral and eastern areas have rolling and mountainous '
21/2 m error in line height measurement at.14 m) is terrains.
O.3 kV/s. The transmission line configurations on the TVA system are:
Eltetric Fields Analysis--Irregular Terrain (i) Single 500-kV circuit with vertical suspension insulators The charge simulation developed in [9) was used to (ii) Single 500-kV circuit with constrained phase simulate the electric field induced by a 500-kV line suspension insulators ev2r a terrain with a general slope of 0*, 5*, and 20*, (iii) Single 500-kV circuit with constrained phase rssptctively. Table I shows the comparison of the suspension ^ insulators with one 161-kV circuit maxitum values of the electric field for these terrains underbuilt as a function of line height for both 9.5 m (30 feet) ~ (iv) Single 500-kV circuit with constrained phase and 12.2 m (40 feet) phase spacing. suspension insulators with two 161-kV circuits underbuilt M:gnitic Fields Analysis All 500-kV lines consist of three 954 kCM, ACSR, bundled conductors per phase, positioned 12 an inverted Magnetic field ' computation is discussed in [2]. equilateral trisagular configuration spaced 7.09 cm (18 Magnztic fields are insensitive to terrain effects and inches) from c'baductor to conductor. The configuration anly slightly sensitive to earth resistivity. The with a vertical suspension insulator has a 12.2 m t2rrain is assumed to be, flat, and a permeability con- (40-foot) phase spacing, while the constrained phase st:nt of p equal to 4nx10 7 H/m is assumed for both air suspension insulator configuration has a 9.15 m and groond. The magnetic field magnitude at ground (30-foot) phase spacing. The 12.2 a phase spacing has 1sval near TVA's 500-kV grid was found to be relatively a 30 m (200-foot) right-of-way, while the 9.15 m small (<.1 Gauss). Also, 'since the induced currents spacing has 28 m (175 feet) of right-of-way.
I - Table 1 ,
ELECTRIC FIEI.D VALUES OVER A TERRAIN s WITH 0*, 5*, AND 20' GENERAL SIhPE Angle Height EMAX (kV/s) ERW (kV/s)
(Degrees) (Meters) D = 12.2 s D = 9.15 a D = 12.2 m D = 9.15 m 0* 12 7.152 ' 6.451 2.221 1.612 Flat 14 5.651 5.023 2.252 1.604 Terrain 16 4.582 4.018. 2.181 1.603 18 3.775 3.252 2.095 1.501 20 3.251 - 2.741 1.942 1.492 II '
5' 12 8.517 '7.503 2.261 1.599 Flat / Rolling 14 6.584 5.755 2.343 1.689 Terrain 16 5.247 4.557 2.349 1.726 18 4.292 3.696 2.297 1.720
, 20 3.576 3.058 2.208 1.681 20' 12 13.855 10525 1.582 1.127 I Rollini 14 9.963 7.995 1.949 1.378 ,
, . Terrain 16 7.562 6.123 2.221 1.575 18 5.960 4.852 2.390 1.712 20 4.830 3.945 2.462 1.788 D e Phase spacing ,
f EMAX = Maximus electric field value along the profile ERW = Electric field value at edge of right-of-way ,
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Mo 330 1
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B . m A detailed descriptien of a typical TVA 500-kV important. The influence of the line geometry en elec-
. transmission line is given in [2]. Measurement sites tric and magnetic fields near the ground can be easily l were selected such .that the resulting data base would quantified using methods outlined ia [3]__a. ssuming the-consist of profiles measured under a variety of line terrain is flat with short ground cover had no shield;- -:
configurations, terrains, and ground cover heights. ing. The spread of the data given in this paper will The major terrain classification was as follows: give a line designer an indication of the maximum (1) Flat terrain--sites with a general slope of less values of both the electric, and magnetic fields at 1 e than or equal to 5*. above ground for various line and topographical config-(ii) Rolling terrain--sites with a general slope oter urations.
'I 5*. The data gives real-world expecurs Irvels in 11.4 The ground cover was classified into four cate- vicinity of energizgd 500-kV transmission lines foe gories. 60-Rz electric field bioeffects reseersh. For this .
(i) Ebort vegetation--less than 15 cm. research work, the maximum value of the " electric field (ii) Medium vegetation--between 15 cm and 110 cm.
I e above ground and the electric field level at the (iii) Tall vegetation--greater than 110 cm. edge of right-of-way are considered important factors.
(iv) Irregular vegetation--a combination of short and These values give upper bounds on exposure levels under medium. the transmission lines and at the edge of right-of-vsy Data was categorized according to both the trans- under normal conditions. i mission line geometry, the measurement site topography. In the statistical summary of the data, cumulative and the ground cover height. probability functions and other descriptive statistical methods [12] were used since the . measurement errors Electric Fields Measurements 2
l have unknown probability distributions.'
The procedures for measuring electric fields near Electric Fields Data--General Analysis EHV transmission lines, IEEE Standard 644-1979 outlined in [3), were used. Electric Fields Measuring Company's The data base generated by the project consists of Model 110 field meters were used for both electric and about 2,700 profiles measured at various locations on magnetic field measurement. A 40-ce clearance between TVA's 500-kV grid. The data base is organized as fol-the field meter and the nearest object is required by lows. Each measured electric and magnetic profile is
. the meter manufacturer; therefore, for ground cover identified by the transmission line name and a data above 60 cm but less than 110 cm, the measurements were collection site number. Geometrical data includes... i taken at 1.5 m above ground level. The electric field tower numbers for towers adjacent to the site, phase was measured at Im above ground level whenever the spacing, and line height. Electrical data consists of
- ground-cover height was below 60 cm. If the height of the line voltage, line current, and power. Weather the ground cover exceeded 110 cm, an area of about data includes temperature and humidity. A general ter-1 square meter was cleared and the measurements were rain description is included in terms of the elevations taken at 1 m above the ground. The field meter was of each of the points on the profile referenced to the oriented to read the vertical component of the field, elevation at the center bundle. The electric field and the distance between the field meter and the -data categorization is shown in Table 2.
observer was maintained at 2 m. A scatter diagram of a random sample of the data The electric field lateral profiles were measured is shown in Figure 1. The scatter is due to the dif-in a direction perpendicular to the transmission line. ferent geometrical line parameters such as line heights The data was taken at 2m intervals for distances and phase spacing. The extreme values are due to dif-between 0 and 12 m and continued at 3 e intervals to ferent topographical factors like rolling terrain, the edge of the right-of-way (30 m). Fields were sea- ground cover heights, and shielding effects. Table 3 sured for transmission line heights of 12, 14, 16, 18, shows a statistical summary of the electric fields data and 20 m, respectively. A general description of the excluding the special sites. The maximum value was terrain, location of trees, and other structures was from a profile measured over a rolling terrain. The i
recorded on the plan view sneets. Iow values near the center phase are due to the pres-The phase voltages and currents were recorded on ence of fences, while the low values at the edge of strip charts at the respective substations; time and the right-of-way are mainly due to the presence of
, other background data as suggested in [3] were also trees.
recorded.
Meter Calibration Three of the meters were checked by the National Bureau of Standards (NBS). The three meters checked j s2 + g were fairly accurate and no recalibration was recom- + +
mended by NBS; but the meter reading deviations from 3 ,
8 known NBS laboratory fields were used to adjust the ! e2' ,
- I g raw data for meter bias. The calibrations of all t'te y , , . , .
- 3
- meters were checked every week using the current = y . , * , ! ! 4 .
injection method and a 1-m2 coil, as recommended in 2 g> g gl g g the IEEE Standard 644-1979. . .g !
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[= ] g T
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IV. 500-kV MEASURED EI.ICTRIC AND MAGNETIC DAi A L L ,
s .
The form for presenting the data in this paper was +
selected so that it could be easily used in transmis- ,; ' ' '
8 .
sion line design and in electric field bioeffects e s e s rs se research [10). In transmission line design, the maxi- ,
sua values of both electric and magnetic fields at 1 m above ground and the field values at the edge of the Figure 1. Scatter diagram of a randos sample right-of-way at 1 m above ground are considered most of the electric fields data.
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. Table 2 FIELDS DATA CATE00 RIES ,
^
- VL. ._, . - E .:
All 500-kV , Fields Data M1gnetic Fields Data ElectricF[ieldsData (Nm detailed analysis) i a Regular Sites Special Sites i (i) Road crossing Unshielded Shielded (ii) Off right-of-way (ROW) .
(trees at edge R0W) (No detailed analysis) ', -
8 .
i !
e i Flat Terrain Rolling Terrain .
1 I s Measurement Height I m . Measurement Height 1.5 m .
(Short ground cover) (Medium ground cover) l s i 1 Ph:se Spacing Phase Spacing Phase S 9.15,a 12.2 m (Turning towers-ir[pasing egular phase spacing)
. l .
l l l 1 Line Height Line Height Line Height Line Height 14 m 16 a 18 a 20 m i
i Table 3 STATISTICAL StP! MARY OF ALL THE ELECTRIC FIELDS DATA (VITHOUT THE SPECIAI' SITES) 4 Distanca from Standard Minimum Maximum Center Phase Mean Deviation Value Value (m) N kV/m kV/m' ' kV/m 'kV/m 0 2678 2.426 1.130 0.098. 6.928 2 2678 2.485 1.062 0.705 6.446 4 2678 2.608 0.922 0.569 5.870 6 2678 2.854 0.865 0.190 .5.850 l' - 8 2678 ' 3.232 0.953 0.000 6.824 10 2678 3.641 ~1.118 0.569 7.585 12 2678 3.939 1.253 0.009 8.540 *
. 15 2676 3.994 1.338 0.473 8.689 18 2671 3.581 1.297 0.141 8.023 21 2659 2.854 1.253 0.000 6.606 24 2569 2.129 1.231 0.000 5.344 27 2350 .1.669 1.056 0.000 4.052 30 2244 1.314 0.874 0.000 3.724 .
, Table 4 .
STATISTICAL SIR 81ARY OF EIECTRIC FIELDS .
DATA AT ROAD CROSSINGS -
6 Distance from Standard M4=Imum Maximum Center Phase Mean Deviation Value Value l (m) W kV/m kV/m kV/m kV/m i g ,. ..
O. 86 2.191 0.971 0.182 5.121 .
2 86 2.245 0.931 0.203 5.034 4 86 2.338. , 0.866 0.442 4.833 ' ;[t .,
6 86 2.477 0.842 0.611 4.870 - .c .
8 86 2.745 0.960 0.734 5.548 to 86 3.089 1.123 0.825 6.531 i
12 86 3.333 1.266 0.896 7.427 15 86 '3.43 1.299 0.952 7.539 ,
18 86 3.255 1.222 0.913 6.826 21 85 2.827 1.201 0.589 5.564 ,
24 83 2.343 1.263 0.000 5.712 27 82 1.913 1.281 0.000 5.906
- 30 80 1.543 1.232 0.000 6.017
I
+' 332 i
. special Sites (i) Flat terrain, at a measurement height of 1 m
- above ground level
. Because of the 2ikelihood of the presence of (ii) Flat terrain, at a measurement height of 1.5 m people, an attempt was made to collect as much data as above grour.d level possible at transmission line road crossings and.at (iii) Rolling terrain, at.a measurement Feight of.1 af . .:
F-; sites where houses were near the edge of the right-of- above ground level way. Electric and magnetic fields profiles were mes- (iv) Rolling terrain, at a measurement h413 ht of sured along the road up to 30 m from the center phase 1.5 m above ground level regardless of whether or not the road was perpendicular This grouping reflects the topography and the to the transmission line. For the data near homes, off ground cover height factors. These categories were the right-of-way, profiles were measured up to abodt further subdivided for electric fields into shielded 60 m from the center phase where permission for taking andunshieldedsubcategories. .
measurements could be obtained. The data from these The analysis of the electric field over a flat '
sites is limited and a detailed analysis is not war - terrain with a 5' general ' slope showed a p,ossible devi-rented. Figure 2 shows the scatter diagram of the ation of 10.7 kV/s for the maximum vertical electric road crossing data and Table 4 gives the statistical field (see Table 1) from the perfectly flat terrain.
summary. Figure 3 shows the scatter diagram of the
- The statistical summary showed the mean and standard data up to 60 m from the center phase. The statistical deviations were within the predicted ranges since the summary of the data is shown in Table 5. flat terrain included sites with general slopes of up
,' ~
, to 5*. The data for the medium and irregular ground cover, as would be expected, have a slightly higher
=-
- mean due to the elight rising of the effective ground l due to the vegetation; and the measurement height of
, 1.5 m is nearer to the overhead phase conductors. The charge simulation method [9] for a rolling terrain with 7 , . a general slope between 5' and 20' showed a variation
't : . of 12 kV/m for the maximum value from the values pre-I..
- 3
+ g , . .dicted assuming flat terrain. Therefore, a larger I *
- N g i + + standard deviation is expected in the data from the ss g
l
- l u o g rolling terrain sites..
g.-r +
g
- Table 6 shows the comparison of the calculated
- I '
n !- values and the medians of the maximum values of the I
measured electric field (EMAX) for the flat terrain I category at the measurement height of I m, with no a
- g , t ! ! . trees at the edge of the right-of-way. Note that the
.s I calculated values are consistently higher by about 0.5
- ; l. ; ; ; , kV/m than the medians of the measured data.
oms =cs enou cuaren e .es - . The most common naturally occurring electric field shielding is due to trees at the edge of the right-of-Figure 2. Scatter diagram of electric fields data way. The effects of tree shielding on the medians of at the road crossing. the measured electric field values at the edge of the
'" right-of-way were quite pronounced. The medians are less than 1 kV/m for all categories. Since the tree 8
locations are random, no general trend with respect to height is expected at the edge of the right-of-way.
=
A more detailed analysis' of the data is given in j .. ,; 1 Appendix A.
e ag
} *- I gg 4 g Magnetic Fields Data
.l ,Itsl*Ile 3
- [.28gl1* + + 8 l .. A detailed data analysis was not performed on the magnetic field data since there are relatively low
[I g li. phase currents (600 A to 1200 A) on TVA's 500-kV trans-
[
87 8j' .*l, 3 mission lines, and since the magnetic fields are not 3 ,8* sensitive to topographical parameters. Table 7 gives
- .}*g;f!*e
.. a statistical summary of the magnetic field data.
I 3h es.e b ,..e. ,. ce urs. , ".. . . V. CONCI,UDING REMARKS l
l Figurr 3. Scatter diagram of electric fields The results of an extensive project to measure and
, data including off of the right-of-way, analyze electric and magnetic fields in the vicinity of TVA's EHV transmission lines have been summarized.
I From the statistical summaries it is possible to j Electric Fields Data--Detailed Analysis approximate the range of electric fields under TVA's
! 500-kV transmission lines for a variety of terrain and l
TVA's 500-kV grid consists of two standard line ground covers.
configurations, one with 9.15 m (30 feet) phase spacing Specifically, the data shows the characteristics and one with 12.2 m (40 feet) phase spacing. Data was of the electric and magnetic fields under TVA's 500-kV-l, collected mainly for line heights of 14, 16, 18, and transmission grid. Although the data spread reflects 20 m, respectively. In order to maintain a 40 cm the measurement errors, transmission line geometry, and
( clearance between the meter and the nearest object as general topography, the medians for the measured elec-
- required by the meter manufacturer, measurement heights tric fields data are lower than predicted when using l of 1 e and 1.5 m were used; therefore, the four main standard methods.
terrain categories are as follows:
t I .
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t 3,
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. 333 N. 1 !
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)
Table 5 ,
i STATISTICAL
SUMMARY
OF EIZCTRIC FIEDS DATA 0FF TE RIGHT-OF-WAY ,
g , , , , ,
Distance free Standard Minimum Maximum Center Phase Mean Deviation Value Value (a) N kV/o kV/a kV/a . kV/s 0 20 2.225 0.8422 0.900 3.900 2 20 2.355 0.7644 1.000 3.750
- 4 20 2.690 0.6269 1.450 3.700
.6 20 3.097 0.6122 2.000- 4.200 $
8 20 3.617 0.6487 2.400 4.800
.. 10 20 4.105 0.7161 2.800 5.400 12 20 4.342 0.7284 3.000 5.650 '
16 20 4.242 0.6424 3.000 5.250 18 20 3.812 0.5510 2.700 4.500 21
- 20 3.197 0.4560 2.300 4.000
- 24 20 2.627 0.3511 1.900 3.300 27 20 2.075 0.3559 1.300 2.700 30 23 1.565 0.3124 0.700 2.200 33 5 1.196 0.4409 0.720 1.800 35 15 1.130 0.1161 1.000 1.350 36 5 0.922 0.3566 0.580 1.400 39 5 0.664 0.3579 0.240 1.150 40 15 0.793 0.1025 0.700 1.000 42 4 0.545 0.2530 0.300 0.900 45 18 0.552 0.1297 0.250 0.740 48 3 0.373 0.1193 0.290 0.510 50 15 - 0.403 0.1409 0.055 0.570 51 3 0.310 0.0692 0.230 0.350 54 3 0.268 0.0529 0.220 0.325 55 14 0.317 0.1088 0.000 0.450 57 3 0.261 0.0201 0.250 0.286 60 16 0.267 0.0415 0.230 - 0.350
-Table 6 COMPARISON OF TE EDIANS OF EMAX WITH COMPUTED VALUES FOR TEE FLAT TERRAIN CATEGORY,
. Median of EMAX (kV/s) Computed IMAX (kV/s)
. . . Beiaht D = 12.2 m D=9.5m D = 12.2 s D = 9.5 e 14 5.30 4.75 5.85 5.19 16 4.06 3.57 4.71 4.13 18 3.09 2.77 3.86 3.36 20 2.71 2.15 3.25 2.79 Table 7
. STATISTICAL SEREfARY OF AIL TEE MAGNETIC ~
FIEDS DATA ,
Distance from Standard Minimum ~Maximus -
Center Phase Meas Deviation Value Value (Meters) N (Gauss /kA) (Gauss /kA) (Gauss /kA) (Gamas/kA) ,
, 2- 2032 0.098 0.042 0.009 1.200 t i . 4
- 2032 0.099 0.035 0.009 0.459 6 2032 , 0.099 0.040 0.007 0.882 .
8 2031 0.098 0.037 0.003 0.473
' '~
10 2032 0.095 0.037 0.012 0.481 -
e 12 2032 0.091 0.037 0.012 0.450 15 2031 0.083 0.034 0.009 0.397 18 2027 0.073 0.030 0.009 0.390 l
21 2022 0.062 0.026 0.005 0.497 24 1994 0.052 0.020 *0.002 0.247 27 1903 0.043 0.017 0.000 0.210 30 1848 0.037 0.016 0.000 0.365
. -w .
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-. 334 f
i
' REFERENCES Data from each of the four major categories, for I
- } a line height of 14 m and a phase spacing of 12.2 m, I
[1] EPRI, " Electrostatic and Electromagnetic Effects for' sites with no trees at the edge of right-of-way of Ultra Nigh Voltage Transmission Lines," EPRI are, summarized in Figure A-jt to Figuri A-(;_ Ge EL-802, Final Report, June 1978. lized electric fields profiles are constructed from
. [2] EPRI, " Transmission Line Reference Book', 345 kV box-end-whisker diagrams of the data with the same ~
and Above," Second Edition, EPRI, EL-2500,1982. distance from the center phase for the respective *
[3] IEEE, "The Electrostatic and Electromagnetic topographical category, line -height, and phase spac- I Effects of AC Transmission Lines," IEEE publica- ing. The electric field at 1 m above ground is high- i tion, course text, 79 EH0145-3-PWR,1979.
- est for sites with a lower line height and a wider :
, [4] D. W. Demo, " Transmission Line Fields," IEEE phase spacing; therefore, the data in these four Trans on Power Apparatus and Systems, Vol PAS 95, cases includes most of the highe'st electric field *
.' No. 5, September 1976.
" Calculating Electrostatic Effects values in the data base. *
[5] ,
oT5verhead Transmission Lines," Proceedings IEEE PES winter meeting,1974. ..
, [6] T. M. McCauley, "EHV and UHV Electrostatic
,, Effects: Simplified Design Calculation and Pre- .
8 ventive Measures," IEEE, Trans on Power Apparatus -
and Systems, Vol PAS 94, No. 6, December 1975. a .
'*', [7] J. P. Reilly, " Electric Field Induction on Long E I ~ !. l Objects - A Methodology for Transmission Line =
l L.4 ::: .: .
- ! Impact Studies," IEEE, Trans on Power Apparatus 1 *- I
- u ig' , ,,
and Systems, Vol PAS 98, No. 6, December 1976. l -- -. - . I t 2 l I lU,
[8] Rish, W. R., and Morgan, M. G. , " Regulating Pos-sible Health Effects from AC Transmission Line g.
-. -}- ,!. i:7* ' TT v' l -
- Electromagnetic Fields," Proceedinas IEEE Vol 67, j. . y ~ hi T i ,
- i'a g, No. 10, 1979.
'[9] Sendaula, Musoke, et al., " Electric Fields
,.!l ! * *{ ,!,,.,
Induced by EHV Transmission over Irregular Ter- [..
- - I rain," presented at IEEE, Summer Power Meeting, I .
j i:. ' -
1982.
i
[10] Bulawka, A. D., et al., "The U.S. Department of :
Energy 60-Rz Electric Field Bioeffects Research," ,
IEEE, Trans on Power Apparatus and Systems, Vol -
PAS-101, No.11, November 1982. 8 .
[11] TVA-Electrical Systems Group "500-kV Electric ,,,,,,,,,,,,,,,,",,,,,,,,,",,,"
and Magnetic Fields Measurement and Analysis Final Report, September 1982, to be published by ..
DOE.
[12] Tukey, J. W., Exploratory Data Analysis, Addison- Figure A-2. Box-and-whisker diagram for flat terrain, Wesley, Inc., Reading, MA. 1977 measurement height 1 m, line height 14 m, and 12.2 m phase spacing.
APPENDIX A DETAILED ELECTRIC FIELDS DATA ANALYSIS en.
The electric fields data are summarized using box-
- and-whisker diagrams [12]. Figure A-1 shows a typical .
box-and-whisker diagram. The diagram summarizes a set .n. .
of data by the median (shown at the centerline), the , I nl ,
I 25th and 75th percentiles (lower and upper edges of the ;
box), and the maximum and minimum values. Extreme data l i:i G l points are also indicated. . ** ' '
- I ~y l Fj l
-~
..- .t. ... , ,
Ul I. . ~I a m o _ . . - - . - -
awae!
i l a!
g . .. . II a i -1 I -'
Y g
+ -
_ . ~ . - r.
_ _ - - . . ~ .- .
3 , , , ,.,
......o..........,
__..m..
o _. _. ._
~ ~ ~ ~ ~
, [,'","[,*,, ,,,,, ,"' Figure A-3. Box-and-whisker diagram for flat terrain, measurement height 1.5 m, line height 14 m, and Figure A-1. Typical box-and-whisker diagram. 12.2 e phase spacing.
e
F. . j 4,
.m .]j n
~
e' '
.ns i
(
. Diseession . l Abdul M. Mousa (B. C. Hydro. Vancouver. r n.d.): I wish to com-
. gratulate the authors for a very interesting paper. Fiss. 2 and 3 indicate o er-that the mean values of the electnc fields under transansmon lines are
. I-* l significantly less than the maximum values. Vinh et al(See Rag-tof -, .,
Ref.13) arrived at a similar conclusion regarding the electnc Seld's in l, , , , .
~
l U r-9
- l 7j] "
Il ll l
. the substations of the American Electric Power Service Corporation.
This phenomenon is one of the mitigating factors where the n =lare al
! ~* O effects of the electric fields. if any. are concerned. The discusser wishes l g * *' - i t ; !. OU .
g;n to make a few comments:
- = = u hii l 1. The electric field profiles were measured using points at 2 3m inter.
vals. This does not allow capturing the point of the ======== elec-8 $8 YI
- l5in tric field and hence it gives a value which is less than the actual saan-y, imum value. So it is not surprising that the calculated manknum -
Ieu- fields were consistently higher than the measured values (by about
. .I l =y 0.5 kV/m in this case).
.... . 2. The authors considered the effect of error in measunas the height of the conductors. A smular concern is the effect of error in measuring
. . . the distance from the centerline. This especially apphes at the edge
. 'of ROW. As shown in Fig. Sa of Ref.14. for X/S a 2.5 and H/S ~ '
4 4 & a .i i. s'. 0.8. the slope of the electne field profile it fairly steep. This, e.evance enou ceavam paaea - u together with the relatively small magnitude of the field. may make Figura A-4. Box-and-whisker diagram for rolling ter. the error relatively high.
rr.in, measurement height 1 m, line height 14 a, 3. In Ref. 2 it is stated that the value m = - 1.4 is approximately ap-and 12.2 a phase spacing. plicable to the flat configuration only when S/N a I and S/D = 33.
'"- These conditions are not met in the application appeanns in this paper. The need for equations like (2.1) despite their limited range and poor accuracy arises from the unsuitability of the format used in an. l. Fig. 8.3.4 of Ref. 2 and other related figures. In that figure. the ratio -
H/D is used on the abscissa. and the ratio #G/Vis used on the or-l -
dinate. Since both quantities are functions of the conductors height
- h. _ ._
.S a... .
_ M; ] g.
AE.. .
(H). Fig. 8.3.4 of Ref. 2 does not show the effect of height on the maximum electric field. A significant improvement is introduced in E ,-- [- Q - - a l p:.
Ref.14 by using the ratio S/D on the abscissa. i.e.. making one axis 3 * ** -
g' . independent of the height (H). However. full demonstration of the j
g
.,l.
===tJ t [ t_:
l
- Ullgj effect of height on the magnitude of the maximum electnc field also requires using the ratio SG/V on the ordinate as shown in Fig. 4.
- 'I I ' 43 'I' l. = Fig. 4 shows that an error in estimating the height results in relatively large errors in estimating the electric field when the ratios N/S and l888- { l S/D are relative!y smaII.
J ] .
e..e ur- I.1. y
. s _s 1
! )( .
- ; ; ; ; ,;, g, ,;,
. Figurs A-5. Box-and-whisker diagram for rolling ter- e.so .
reia, measurement height 1.5 m, line height 14 m, e . unc to uma vettast and 12.2 a phase spacing. , ,
s.25 .
S/D-P.U.
ACID 80WI2DGEMENT , .
a '-
to The help of Dr. D. R. Bittaan of TVA in the sta- . e.se .- -
(
tistical analysis of the data is gratefully. acknowl-so edged. The data was collected and analyzed by TVA's g Electrical Systems Group for the Department of Energy, ass ,
Division of Electric Energy Systems, through inter. e.is -
esency. agreement DE-AIO5-79ET29016.
IZGAL NOTICE e. . . .
This report was prepared'by the Tennessee Valley Authority (TVA). Neither TVA nor any person acting on t its behalf: . ..
e.es . -
- c. makes any warranty.or representation *, ' express ,
er implied, with respect to the use of any information -
7 goatained in this report, or that the use of any infor- . . . . . . . . :- -
metics, apparatus, method, or process disclosed is this e.5 s.e s.5 a.s 3.5 3.s 35 report may not infringe privately owned rights; or H/$-P.U.
- b. assumes any liabilities with respect to the tr.c3 cf. or for damages resulting from the use of, ony Generalia*d grapha for the effect of height on max. electric fieldt horisontal configuration.
infsroation, apparatus, method, or process disclosed in
'this report. 4. The data in the paper show the statistical variations of the electric This report does not necessarily reflect the field due to vegetation and topographical factors. Two other views sad policies of TVA. superimposed statistical variations exist: one due to the fluctuation
. . . ,c> _
,e * . -
,,.a 336
~
ii in the vokase of the conductor, and the other d' ue to the change of Ground Level for the Horizontal, the Deha, and the Inverted
- 4 ses due to variations in conductor temperature. Delta Configurations," Trans. Canadian Communications and
- o 3. In the paper, exposure to electric fields on the ROW is considered to Energy Conference, JEEE Parblicatioer no. 82 Chl825-9,spp.
be quantified by the maximum electnc field and by the electne field 30 55, Oct.1982. 1 i
at the edge of the ROW. .Deoretically speaking, this is not adequate - . -
because those two points can be interconnected by many 3:aphs y' *~ -,
$4anuscript received July 14, 1937.*
'i
. some of which will represent a higher everage intensity than others. ;
Perhaps it would be useful to also use a factor similar to the - '
" Flooding Factor" proposed in Ref.14. M. Sendaula, D. W. Hilson, R. C. Meyers, L. C. Akees, and B. J.
- 6. It is stated in the paper that "where the height of ground cover ex- Woolery: We appreciate Dr. Mousas' comments and interest in our ceeded 1.lm, as area of about one square meter was cleared and paper. The main objective of the paper was to describe the data base on l4 . measurements were taken at Im above ground." Thus the meter was electric and magnetic fields measured near TVA's 500.kV transnussion shielded by the tall vegetation surrounding it. The discusser has res- lines. The analysis was done painly for the organization of the data
- 1' ' ervations regarding the value of measurement taken at such shielded base. In the detailed statistical analysis, the raw electnctfield data were - -
locations. normahzed to 500 kV base. Line height for every measured electric field
- 7. De readers will find it tiifficult to locate the references listed in the lateral profile was used as a sorting key. Therefore', the statistical varia-paper since most of them do not give the 'page numbers and one of tions, for example in Fiss. A.2 to A-4, are due to terrain charactenstics.
them (Ref. 5) does not even give the publication date. It is requested Clearing -one square meter, when measuring electric field in tall that the authors kindly add the missing information before vegetation was to ensure the 40 cm clearance between the field probe publishing the paper in the Transactioist. ' and the nearest object. Standardization of this procedure may be re.
. Notwithstanding the above comments, this paper is a valuable
- addition quired.
I to the literature. .
REFERENCE.
li
- REFERENCES .
[5] D. W. Deno, " Calculating Electrostatic Effects of Overhead
[13] T. Vinh, C. W. Yi, and C. H. Shih, " Measurements and Analysis Transmission Lines," /EEE Trans. vol. PAS.93, no. 5, pp.
of Electric Fields in HV and EHV Stations," IEEE Trans., vol. 1453-1471, Sept./Oct.1974.
PAS.101, no.10, pp. 4122-4130. Oct.1982.
[14] Abdul M. Mousa, " Generalized Profiles of the Electric Fields at Manuscript received September 26,1983. ,
'i ed . . .
O
- , , . 5 7 ', 3333 IEEE Transactions on Power Apparet:s and Systems. Vol. PAS-lo2 No.10. October 1983 1
8 MEASUREMENTS OF ELECTRIC AND MAGNETIC FIELDS l 4 . .
IN AND AROUND HOMES NEAR A 500, kV TRANSMISSION,LINE -
y _, ;,
R. J. Caola, Jr., Member D. W. Deno, Senior Member V. S. -W. Dynek, Member General Electric Company General Electric Company Public Service Electric & Gas Co.
Schenectady, New York Pittsfield, Massechusetts Newark, New Jersey Abstract EASUREENTS f In response to the public's concern about living Lo' cation near a 500 kV transmission line, Public Service Electric & Gas Company of New Jersey conducted mea- The' measurements were made adjacent to the New
, surements to determine the magnitudes of electric and Freedem-Deans 500 kV transmission line in Hightstown, magnetic fields in and around homes adjacent to the New Jersey. They were perforned over a two-day period line. Results of the measurements indicated that at three. homes. .Two of the homes (1 and 2) were close house walls provided shielding from the electric field to the transmission line and the other (3) was con-and that the electric fields created by house wiring sidered to be remote from it. At each home measure- I were a significant part of the total field inside the ments were taken both outdoors and indoors. The '
homes, relative position of the transmission line and homes I is shown in Figure 1 and a cross sectional view of the INTRODUCTION line is shown in Figure 2. ,
In recent years the general public has become in-HOUSE # 3 creasingly aware of f actors affecting the environment. 13 kV 0lSTRl8UT10N I1 The impact of this awareness has been felt in many LINE !
areas of the electric power industry. In high voltage 500tV -
.l transmission, recent research conducted to inves- 1 MILE FROM TRANSMIS$10N tigate biological effects of electric and magnetic 500 kV LINE LINE fields is a result of this public concern and the con-cern of the utilities which serve the public [1]. A -
first step in environmental research is to determine g$, -
existing levels of electric and magnetic fields and thevoltagesandcurrentstheyinduce[2]. HOUSE # 2 The purpose of this paper is to describe the re-sults of a project in which measurements were per. 4 4 6 m ->
formed around and inside houses near a 500 kV trans-cission line to determine the magnitudes of electric @ 82.5m .
field, magnetic field and space potential. Specif- HOUSE # 1 ically, the measurements were made to illustrate the '
following characteristics of electric and magnetic fields:
- 1. Their levels around the houses. Figure 1. Overhead view of measurement site.
- 2. Their penetration into the houses, p
- 3. The relative magnitudes of fields produced by the 4 [LgjowELD transmission line and those produced by the house 10.7m wiring.
. 4. Their predictability by calculations. OO
- 5. Their ability to induce currents and voltages in
PHASE CONDUCTORS the bodies of people existing in them. -1821 IN. (4.63 cm )
d i OO ACAR 54/37 9.5m AT 18 (N.(45.7tm ) SPACING
[ OO 17.7 m 83 kH 164-1 A paper recommended and approved by j f f f f j the IEEE Transmission and Distribution Comittee / / / / / /
cf the IEEE Power Engineerins Society for presen-tation at the IEEE/ PES 1983 k' inter Neeting, New Figure 2. Cross Section of New Freedom-Deans 500 kV York. New York, January 30-Tebruary 4, 1983.
~
transmission line (midspan) between poles Manuscript submitted September 2.1982: made 56/5 and 56/6 looking southwest to north-svailable for printing November 16, 1982. east.
0018-9510/83/I000w3338101.00 C 1983 IEEE 1
i:t
,, , L-I 3339 % ,
Inside, both hirinntn1 and' vertical components d .
Instrument'ation electric field were me sured. Th7 readings were taken d Measurements of magnetic field, space potential, near walls facing the transmission line and at the
, center of the rooms. Figure 4 shows the orientation currents and voltages were made with a Power Frequency of the rooms in Houses 1 and 2 with . respect toJhe -
Fir,1d Meter Model 110 manufactured by the Electric transmission line. At each home;' measurements 'were Field Peasurements Company. The electric field was obtained with house power both on and off. (House measured with a Model 100 field meter produced by the power was shut off by opening the house circuit -
same company. For measurements of electric fields cutside the homes, a two meter handle was used on the breaker). At House 2. measurements.were obtained not Field lieter in order to perturb the field as little as only with house power on and off, but also with the possible. Inside, however, because of lack of space, transmission line both on and off. Four cases were a shorter handle was frequently used. investigated, which illustrated the following:
- 1. With the line and house power on, the total ielec- -
For measurements of magnetic field, the Model 110 Met;r was used with a sensing coil. tric field was measured.
Scope
- 2. With the line on and house power off, the electric field from the line was measured.
The electric and magnetic fields which were inves- With the line off and house power on, the electric '
tigated at the homes near the transmission .line ema- 3.
nated from several sources. Mainly of interest were field from the house circuits was measured.
those produced by the 500 kY transmission line. 4. With the line off and house power off, the elec-An ther source of fields was a 13 kV distribution cir- tric field from all other sources was measured.
cuit running parallel to the transmission line between the line and the homes. No attempt was made to sepa- By doing this, the electric fields produced by the rate the effects of the distribution circuit.itself on different sources were measured.
the ettetric and magnetic fields. (Measurements indi-cated a very low electric field from the distribution circuit.) A third source was the wiring present in thi homes. The relative positions of these and other ,
influencing f actors are shown in Figure 3. (Because TRANSMtSSION LINE the electric field was of greater interest than the tagnetic field, many more electric field measurements HOUSE 81 HOUSE 82 were made and more space is devoted to them in this
' WALL FACING TRANSMISSION LINE Paptr). WALL FACINGTRANSMISSION LINE O
500tv TR ANSMIS$10N { D
~
LIN E E
r-D(WNSTAIRS D@NSTAIRS
' H 13tv A '
A 8 DI STRIB UTION A B
~~~~
LlHE HOUSE # 1 h a SNOW C C FENCE UPSTAIRS UPSTAIRS Om 32 m 46m 62m 82.5m Figure 4. Plan view of downstairs and upstairs of Figure 3. Cross-se'etional view of area between trans- House 1 and House 2 with room designations.
mission line and House #1.
Space potential measurements provide support for The three houses at which measurements were made measurements of electric field. At House 1, measure-were similar in appearance and no attempt was made to ments of equipotential lines were made outdoors near investigate such factors as differences in construc- the wall facing the transmission line. These helped tion or methods of house wiring as they affect the Glectric field inside the housts, determine the behavior of the electric field at this
- boundary. Inside the first home, space potentials Electric Field and Space Potential ,were measured along the walls facing the line with house power both on and off. -
Electric field measurements included profiles Magnetic Field starting from the transmission line and extending toward the hones. Because there were several objects which acted to perturb the field between the trargsmis- A profile of the magnetic field was measured be-sfon line and the houses, another profile was measured tween the transmission line and the homes. Inside the in the opposite direction, where the field was unper- homes, measurements were made at the centers of se-turbed. Spot checks were obtained at the home remote lected rooms. All readings were taken with both house from the line. power and transmission line on.
)
.. - 33 #
TAR.E 1: ELECTRIC FIELO VALUES INSIDE NOUE 2 TRANSMIS$10N LIE POER ON TRANSMISSION LIE POER OFF
~
.. HOUSE POER ON HOUSE POER FF MOUSE POER ON MOUSE POER FF -. - I Light Light -
Light Li ht I '. ' wr 0N Orr IN -
l
. ROOM A
- 1 VERT. EL. FIELO (V/s) "
AT OUTSIDE HnLL: * ' ', , .
1 m High 3.5 2.2 5.3 5.0 0.60 At Ceiling 8.5- 18.0 15.0 6.5 0.15 CENTER 7 ROOM:
1 m High . 2.5 3.6 - -
HOR. EL. FIELD (V/m) .
AT CEILING: .
- ~' '1 a from outside Wall 7.2 .12.0 3.0 9.0 . 0.1 Center of Room 3.0 5.0 - - -
ROOM B YERT. EL. FIELD (V/m)
AT OUTSIDE WALL:
1 m High 1.7 3.0 2.3 2.0 0.15 At Ceiling 14.0 ,
- 20.0 7.3 6.0 0.25 . ,,
CENTER OF ROOM:
1 m High 2.2
- 3.5 - - -
~
I HOR. EL. FIELD (V/s)
AT CEILING:
1 m from Outside Wall 7.5 16.0 24.0 8.0 0.40 Center of Room 3.5 12.0- - - -
ROUMD VERT. EL. FIELD (V/m) l AT DUTSIDE WALL:
1 m High 0.8 - 1.6 At Ceiling 5.0 - 15.0 CENTER OF ROOM:
. I a High 2.1 - 3.5 HOR. EL. FIELD (V/m) ,
AT CEILING:
1 m from Outside Wall 6.5 5.0 5.5 Center of Room 9.5 9.3 1.0 Note: Outside wall is wall facing transmission line.
Induced Body Currents and Voltages ment in which the house power was switched on and off while the transmission line was both on and off clear-These measurements were made only at House 1. One ly illustrates this point. The results, which were measurement was taken in the right of way between the obtained at House 2, are shown in Table 1. Table 1 transmission line and the home. Measurements were illustrates the following main points.
also made at work areas in the kitchen.. +
Transmission Line Power Off: With the transmis-
- . sion line off, the electric field increased between ,
ESULTS one and two orders of magnitude when house power was '
turned on. This shows the substantial effect of house Electric Field and Space Potential at House 2 circuits on the electric field. Also, note that switching lights on and off had a substantial effect -
The most important observation was that the levels in some locations.
of electric field and space potential inside homes near the transmission line were considerably affected Transmission Line Power On: With the transmission by energization of house wiring circuits. The experi- line on, sne electric tiera cnanged by at least sixty we--g*we--ee-*~mm e- y ev-a w e we,-w ee v eve-==<--e ,w_g-,-e-.--g-e
s'
., . o
,_, 3341- !
+ %
TABLE 2: ELECTRIC FIELD VALUES INSIDE HOUSE 1 :. ,
'
- ROOM A ROOM C - ROOM D ROOM E HOUSE POWER HOUSE POWER HOUSE POWER HOUSE POWER - .
~~~~'#
OFF ON OFF ON OFF ON OFF ON VERT. EL.' FIELD (V/m) .
AT OUTSIDE WALL:
1.0 5.0 - - 0.35 1.0 0.50 1.5 '
1 O High 0.60 1.1 At Ceiling 6.0 20.0 - - 0.60 3.5 ,
CENTER OF ROOM: 3
,1 D High - - 3.5 2.3 0.50 2.5 1.00 7.0 HOR. EL. FIELD (V/s)
AT CEILING: '
. 1 a from Outside Wall 7.0 10.0 - - 1.10 5.5 0.75 5.0 i 7.0 ~ 6.0 - - 0.90 3.5 1.50 1.8 Center of Room TABLE 3: ELECTRIC FIELD VALUES INSIDE HOUSE 3 4
' ROOM D ROOM A HOUSE POWER ON HOUSE POWER OFF HOUSE POWER ON HOUSE POWER OFF 4
Light Light Light Light OFF ON OFF ON 4
VERT. EL. FIELD (Y/m) ,
AT OUTSIDE WALL:
6.0 3.0 0.30 4.5 4.0 0.40 .
1 o Hi@ 13.0 0.80 At Celling 12.0 12.0 0.45 -16.0 ,
4 CENTER OF ROOM:
1 o High 3.0 3.0 0.30 ,
8.0 4.0 0.45 1
HOR. EL. FIELD (V/m)
? AT CEILING:
5.5 5.5 0.30 8.0 4.5 0.15 I o from Outside Wall center of Room 1.8 1.9 - 0.20 3.0 4.5 0.12 ;
* Note: Outside wall is wall facing transmission line. r I percent in 12 of the 15 measurement locations when V/m at all measurement locations. When the house cir-hiuse power was turned on. This indicates that the cuits were energized, the field levels increased be-effect of house power was evident, even with the tween one and two orders of magnitude, to levels sini-transmission line energized. Also notice that the lar to those with house power on in the other homes.
magnitude of the electric field stayed between 1.0 and Here again, in Room D, changes produced by switching 20 V/p whether the house power was on, the transmis- on a light were recognized.. These measurements, which siin line was on, or both were on. support those taken at House 2 with the transmission -
- line off, are shown in Table 3.
The results of these measurements indicate that .
Hessurements of electric field and space potential ,
olectric fields present in this home near the 500 kV trtnsmission line were due to house wiring as well as outside House 1 indicate the shielding provided by the .
the transmission ifne. walls for the inside of the home. In the yard adja-cent to the home, measurements of vertical and hort- ,;
Electric Field and Space Potential at Houses 1 and 3 zental electric field were performed in order to con- -
struct a profile from the road to the wall of the i Results similar to those observed at House 2 were house. The results are shown in Figure 5. As the <-
wall was approached, the vertical field decreased S**
(bserved at House 1 and Housd 3. At House 1, the steadily untti, at the wa11, it became zero. The olectric fields measured with house power on were
- r. greater than those with house power off at 13 of the horizontal field, however, increased steadily as the h 15 measurement locations and greater by a factor of well was approached. This is primarily because the
- y* i two or more in 10 of 15. (1he transmission line was well appears to be a plane at constant voltage and always energized in these measurements.) Results are causes the electric field lines to terminate upon it shown in Table 2. horizontally. Figure 6 illustrates this point in a
, slightly different way. Shown there is the 52 volt At House 3. remote from the line, there were very equipotential line. Since electric ffald lines are j low values of electric field with house power off. always perpendicular to equipotential lines Figure 6 ,
Like the circumstances in House 2 with both the line graphically illustrates the change of electric field I and house power off, the electric field was under 1.0 from being principally vertical. to mostly horizontal j
5
> . ; 3342 as the tal? 1s approach:d. This also indicates that El;ctric fields and space potentials measured at the wall appers to be a plane of constant voltage. the landing of the stairway of House I were greater The last measurement of horizontal electric field in- than anywhere else in the house. The reason was that dicated 90 V/m at one-half meter from the house. How- a large window facing the transmission line provided
, ever, horizontal field values from Table 2 show no les; shielding than the rest of the wall. gThis effect.'. a values close to 90 V/s. These measurements indicate is generally true of less conductive materials, glass that the wall does provide shielding from the electric being a better electrical insulator than brigk or field. Figure 7 shows the composition of the wall wood. Unlike glass, brick and wood absorb moisture facing the transmission line for House 1 and House 2. and therefore become slightly conductive.
. The degree to which the houses provide shielding from the electric field can also be roughly determined HOUSE 81 HOUSEf2 ,
by comparing the electric field measured inside the e house (with house power off) to the value of the elec- g tric field measured outside adjacent to the house. . ROOF From Figure Al, the measured vertical electric field -
adjacent to House 1 was approximately 80 V/s. The 9 WINDON WIN 0(Mt measured values of electric field inside. Houses 1 and 2.with house power off range from 0.5 to 20 V/m. If '
we use 10 V/m as a typical value,. the degree of BRICK BRICK WOOD WINDCMI shielding provided by the house is 8:1 (80 V/m:10 V/s).
WOOD WlND(M 100 ' ' ' ' ' ' ' ' ' '
WALL FACING TRANSMISSION LINE WALL FACING TRANSMISSION LINE 90 - '
80 -
VERTICAL. - Figure 7. Side view and composition of wall facing
.g FIELD transmission line for House 1 and House 2.
y70 - -
An ther observed phenomenon was the noticeable. .
d 60 electric field present near electrical appliances.
Table 4, [4] shows the electric fields measured near d.50
- 7 typical _ household devices.
o iE 40 - -
TABLE 4: ELECTRIC FIELDS (60 H2)
U GENERATED BY APPLI ANCES 9 30 - -
w HORIZONTAL -
ELECTRIC FIELD
- 20 - FIELD . ITEM (V/m) 10
- - ELECTRIC BLANKET 250 BROILER 130
, , , , , , , , , , STEREO 90 0
[ 0 2 4 6 8 10 12 14 I6 18 20 22 REFR ERATOR
~
DISTANCE FROM WALL OF HOUSE -m HAND HIXER 50 l
i4 TOASTER 40 VAPORIZER 40 Figure 5. Variation of vertical and horizontal COLOR TV 30 electric field near House fl. C0FFEE POT 30 VACUUM CLEANER 16 CLOCK 15 l
' ' ' FLUORESCENT LIGHT (OFFICE) 10 ELECTRIC RANGE 4 y INCANDESCENT LIGHT BULB 2 a4 - -
i g
- Measurements made 30 cm from appliances.
8 " ~
3 Magnetic Field
~
- 2 . 52 POTENTIAL - Measurements of magnetic field were made to com-LINE pare the levels found outside the houses with those l E inside. At House 1, the field present in the parking -
E, _ _ lot adjacent to the house was around .0025 gauss.
.. Inside, the maximum magnetic field averaged .0024 gauss (all measurements were either .0025 or '.0023'
, , , , , , gauss). Line loadings averaged 1172 amperes. Similar I 0 1 2 3 4 5 6 levels were measured at House 2 during line loading of I 1124 amperes. At House 3, remote from the line, the DISTANCE FROM WALL OF HOUSE-a maximum magnetic field inside the home averaged .0015 gauss. During these measurements, line loading was Figure 6. 52 volt space potential line measured at 650 amperes. In all cases, house power was on when wall of House #1. the measurements were taken. Therefore, it is diffi-s 1
~
I 3343
,j * .
C is the person's capacitanc] t3 ground. . ,!
cult to determine t:hether tr n;t current flowing in i hous2 wiring made a significant contributiin to the C % 125 pF (under dry conditions). l
, magn: tic field. Assuming the walls of the house to be I conenagnetic and non-conducting with respect to mag- , . .
n; tic field, it would seem that the walls would pro- C 5uA U- * :'
vide little shielding for the interior. V= 42 = 16.0 volts 377 x 125 x 10 -
Induc?d Body Currents and Voltages This indicates that the established,' simple formu-lae for uniform fields closely predict field induced M:asurements of currents and voltages induced in currents and voltages in the human body.
the human body were made on two subjects standing in the right-of-way approximately 33 meters from the 500 Measur aents were also made in the kitchen area of kV transmission line (See Table 5). The measured cur. House 1. The results are'shown in Table 5. The mea-r nts and voltages were those induced by the electric surements made with house power on and off illustrate field and were measured In one in a connection case, between readings were 0.70 the pA the increase of currents flowing in the body as the b:dy and ground. electric field increases. The other measurements show and 15 volts; the other 0.73 W A and 16 volts. ' A check the magnitudes of leakage cur' rents which can be pro-of the measured data with an approximate calculation duced by appliances. The ANSI standard maximum leakage fallows [3]. - current from stationary appliances is 750 v A. This
- standard is much higher than any currents measured in TABLE 5: CURRENTS AND VOLTAGES INDUCED the kitchen area.
IN THE HUMAN SODY
- CURRENT VOLTAGE CONCLUSIONS THROUGH ACROSS SUBJECT'S BODY (VOLTS) 1. Inside homes, the magnitudes of electric fields LOCATION BODY (uA) produced by house wiring were in the same range as NEAR SNOW FENrE: those produced by the transmission line.
Subject 1 0.70 15.0 16.0 2. At Houses 1 and 2, the energiration of house wiring Subject 2 0.73 changed the local electric field by a factor of two '
or more at 16 of 30 measurement locatinns. (See CENTER OF KITCHEN: Table 1 (TRANStilSSION LINE POWER ON) and Table II)
House Pwr. ON - 0.35 --
(Subject 1) 3. The walls of the homes acted to shield their in-House Pwr. OFF - 0.008 0.20 teriors from exterior electric field effects.
(Subject 1) However, walls with large windows did not shield as effectively as solid walls.
HOUSE POLTR OM:
- 4. Calculated and measured valets of the electric Touching Sin 6 field showed excellent agreement, especially in
& Refrigerator areas where the transmission line field was un-(Subject 1) 76. 35.
- 77. 45. perturbed.
(Subject 2)
- 5. Currents which can be prodyced in the body by
- Mein touching kitchen appliances were greater than cur-currentthreshold is 1.1 mA.of3]p[erception for men for alternating rents induced by the electric fields present with-ANSI standard maximum leakage current from station- in the home.
ary appliances is 750 DA. [4]
- 6. Calculated and measured values of voltages and The equation
- for current through a well-grounded currents induced in people standing near the -
person is as follows: transmission line showed excellent agreement.
I = 5.4 x 10-9 x E x h2 mperes A
REFERENCES Where E is the unperturbed electric field in V/m ~
a;.d h is the person's height in meters. i
- 1. Transmission Line Reference Book. 345 kV and Above/ j The data was recorded for the subject standing be- -
Second Edition. . Electric Power Research Institute.
tween points at which the vertical electric field was Palo Alto, California,1982, Chapter 8. An exten- i 25 V/m and 60 V/m. Taking an average: sive list of references on this subject is con-tained in references 38 through 65 in Chapter 8. -
E = 60 + 25 , 43 yj,
'. 2. J. Patrick Reilly and M. Cwiklewski, " Rain Gutters ):
- Hear High Voltage Power Lines: A Study of Electric h = 6 ft. = 1.8 m ,
- Field Induction", IEEE Transactions on Power ;
Apparatus and Systems. April 1981. Vol. PAS-100, ;
I = 5.4 x 10-9 x 43 x 1.82 No. 4 pp. 2068-2081.
1 = .75 u A 3; Transmission Line Reference Book 345 kV and Above/
- 5econd Edition, Electric Power Research Institute. **
Neglecting any resistance to ground, the violtage Palo Alto, California,1982, Chapter 8.
is calculated as follows:
- 4. H.A. Kornberg, ' Concern Overhead", EPRI Journal, June-July,1977.
V = ,, f
q-
' ~
3344 > .
APPEND!I 10,000 , , , , , , -
Sp00 - -
i
. Figures . Al artd A2 show comparisons between mea- 6p00 -
sured and calculated values of vertical electric ,
field. Al shows these values for a profile extending .
4000 e. -
C -
- ~
frce the transmission line toward the homes. In a 8
~
computer program solution of the two dimensional field e cquation, the transmission linc, snow fence and dis- a -
tribution line with 11 associated conductors were g 2p00 - e ,
m x modeled. The reason that the measured values run 5
- lower than those calculated (beyond about 50 m) ise ' "
that the shielding effect of the houses was not E l.000 - -
modeled. Tall objects can perturb electric fields for . g 800 -
. a significant distance at ground level. .
as 600 . g X-ME ASURED. . ,
0-CALCULATED E 400 -
1 y
10,000 , , , , , ,
8000 - ,
- .O 200 - .I -
'6p00 - ,
y ,
4p00 _ a , ,8
- a
, 5 100 . -
- I 80 -
t e -
$ 2p00 -
h 60 -
40 * ' I j ,
$ ,0001 800 - o . X - MEASURED .
' 20 - -
$ 600 -
t 0 -CALCUL ATED _
j d e C 400 - -
0
-d o 3 8 52 20 40 60 80 100 120 14 0
_j 200 -
- I -
DISTANCE FROM TRANSWISSION LINE
"' 1 CENTER LINE OF CONDUCTORS-m N c' "'"mo,~
? - ;f %% -
Figure A2. Comparison ' of calcuiated and measured E 60 - 8
- **x,an: s -
values of vertical electric field.
40 -
o [' 8 a
(Profile extends away from House #1.)
20 -
- 8 -
Don W. Deno (M'60) was born in gi -
+- Illinois on Septem-
' ' ' ' ~ @'3Evanston, r ber 3, 1924. He received a 0
0 20 40 60 80 10 0 12 0 14 0 h B.E.E. from Cornell University in February 1949. He received HORIZONTAL DISTANCE FROM his M.E .E . and Ph.D degrees 500kV TRANSWISSION LINE CONDUCTORS-m from the University of Penn-sylvania in 1968 and 1974.
Since 1949 he has been Figure A1. Comparison of calculated and measured / with the General Electric Com-values of vertical electric field. pany working with electronic (Profile extends toward house fl.) h systems, electrical systems, mechanica' systems, and control systems. He has worked in the Power Circuit Breaker Department of G.E. Co.
Another profile was measured in the opposite di- Since 1971 he has been a research engineer at Project rection where there were no objects or voltage sources UHY.
which would perturb the field of the transmission Don Deno was the principal investigator in the line. These measurements agree very closely with cal- area of electric and magnGic field effects of over-culated fields out to a distance of 400 feet from the head lines. He has co-autiored the chapter on " Field line. The results are shown in Figure AZ. Effects of Overhead Transmission Lines and Stations"
. of the Transmission Line Reference Book 345kV and Since the two sets of measureme'nts comprising Above/2nd Edition. The work included calculaton and Figure Al and A2 yere recorded at different times, the measuring techniques of electric and magnetic fields, values for height of the line above ground and voltage characterization of currents induced in persons and -
varied between the two cases. The height of the objects, studies of spark discharges, response of lowest phase was 58 feet and the line voltage was 510 people to short-term exposures to transmission line kV for Figure A1, and 57 feet and 507 kV for Figure fields, methods of shieldir.g. etc. This work was ap-A2. The line heights were estimates taking into ac- plied in testimony on 765 kV power transmission lines count line loading and ambient temperature. Voltages for the New York State Public Service Comission.
and line loadings were obtained from the local substa- Mr. Deno is a Registered Professional Er.gineer in j tion. the states of New York and Pennsylvania. !
i
- l
. ' g l },
. [t n
3345 D l"
} '
Y, l Ralph J. Caola, Jr. was born where Eo is the ambient electric field p* + m August 4, 1954 in Troy, New d = (1 - R,*/R ') f T York. He received his B.S. sr = sr-Wuso I
. and H.E. degrees in Electric sris the relative dielectric constant of the -she!!. .
C-
{
~ (is the conductivity of the shell _ - . .r
)
- 5 selaer Power Engineering Polytechnicfrom Rens-Institute so is the permittivity of free space I
w is the radian frequency
' in 1976 and 1977 respectively, Hr. Caola worked for New As an example, Douglas Mr wood at 25% moisture content has a com-s York State Electric and Gas plex relative dielectric constant sr = 1.97 - J 4.33 at 60 Hz[2].Thus.
L Corporatfon in the Transmis. for a she!!cf 3m radius and 20 cm thickness I . sion and Interconnection Plan. f I k A b.7 the General Electric Company in 1977. O -5ning Section before joining which represents 4 db of shielding. E = 0.64 Eo
. 4 Certainir. such important influences as house wiring and plumbing He presently works in the Transmission Engineering are neglected in this simple model. These factors would probablyin-Section of the Electric Utility Systems Engineering crease the shielding to levels tomparable to those reported in this paper.
Department. Special interests include protective re- However, it may be possible to include these factors by using an " effec-laying, substation modelling and electric field and tive" wall conductivity. The extent to which shielding can be accurately corona performance of transmission lines. Mr. Caola modelled theoretically without undue complexity remains to be seen. is a member of Tau Beta Pi and Eta Kappa Nu. ,. O power transmission line
- - Vincent S. W. Dymek was born 5 in Johnsonburg, hew Jersey on g g October 7, 1932. He received a B.S. degree in electrical Eo - Ambient Electric Field
,,s engineering from t.ehigh Uni-s_ versity, Bethelem, Pennsyl- t 6 .
vania in 1954. Except for two years as a comunications of- shell
' ' ficer with the United States
,' [R Air Force Mr. Dymek has been
/
with Public Service Electric [P '
$ .and Gas Company from 1954 to 1
R2 , A _, the present. He has worked in transmission system planning; substation operation and maintenance; trans-mission operation and maintenance, construction, de-
/ / / /' / / / /// //
sign, and project management. .. He is a member of the IEEE Power Engineering earth S ciety and a registered professional engineer in the Egure la. State of New Jersey. Hemispherical shell ticar a transmission line. Discussion i '
- C. G. Olsen (Washington State University, Pullman, WA): The authors * '
1[f this paper have made a very valuable contribution to our knowledge 2 tbout the electrical environment near power lines. The mesults of the E, study will be useful to engineers who need to know about the effects of - Uniform Ambient electric fields. Electric field t 0 I have several comments about the work and a suggestion for future efforts which may strengthen the conclusions of the study.The techni- ', que used in the study is purely experimental. Measurements such as the ones described are essential for determining the fields inside a particular / e, c l strucure or of validating any theory of shieldins by structures. How- . p', RI
, e ever, without extensive data and creative interpretation, measurements I do not provide insight into the means by which building material and construction influence shielding effectiveness. Yet this information is to ) ,
l necessary if general statements about the shielding space effectiveness .
, ,/
/ '
3 i Cf buildings are to be made. . I I would like to ask the authors to comment on the value of a theored- ' . ca! study designed to supplement the work reported in this paper. To be f more specific, I would like to describe a very simple shielding problem which could be used as a starting point for such a study. Consider a hemispherical shell-(which crudely re, presents a building) which is located near a power line as shown in Eg.1.a. The shielding effec- ~ tiveness of the shell can be established by determining the electric field
- EgureIb. '
inside the shell as a fraction of the ambient field (i.e., the field in the Equivalent problem after application of image theory. tbsence of the shell). If the ambient field is approximately uniform over ",! the volume of the shell and if image theory is used then this problem REFERENCES reduces to finding the field inside a spherical shcIl immersed in a uniform electric field as shown in Fig.1.b. [1] M. Zahn, Electromagnetic field Theory, John Wiley, New York Following the technique outlined by Zehn, a simple expression for 1979, pp. 284-297. , the electric field (entirely vertica!) inside the she!!is [1]. [2] W. R. Tings and S. O. Nelson, " Dielectric Propert,es i of Materials for Microwave Procesung Tabulated," Jour. Microwave Power, 9 'O E, g(i),3973, E= ' I * *
- N Manuscript received February 23.1933.
r r
e . 3346 V. Cateca (Consultant, Bergenfield, NJ): The authors make a modest on this subject cnd published to document a perspective cf nominal though valuable beginning in an area which has been lacking of con. public exposure to electric fields. The discussions are commented on as
. crete published data. They do not however, address an almost obvious follows, important cuestion. This is: if the houses were situated in an electric S. A. Sebo: An serial photo is enclosed to augment the data. Tbc . . field larger than the 80 V/m of the paper, would the shielding factor re- phasing of the transmission line was ABC from top conductor to bot. - a main the same 8:1 so that the internal 10 V/m average field would in- tom. The geometry of the transmission line relative to the houses is illu-crease in proportion to the external field 7 Intuitively the answer would strated in Figs. I through 4. Test locations are described in the Electric appear to be in the affirmative; but the raatter warrants some thought. g - .
The question has practical pertinence because there are quite a few w L > 7. ;, "* houses appreciably closer to HV and EHV transmission lines than m s s#
- g g w* ,
House #1 or #2 of the paper; and the lateral electric field profiles of w l . . . most of these lines tend to extend outwards farther than that of the 3
, "M-. * . '
compact vertical conductor configuration of the 500 kV line of the G r . paper. A level of about 1000 V/m is not uncommon near the edges of i jr s i their right-of. ways. Moreover there are also many homes or occupied - i structures clow enough to distribution lines such that despite the lower g y 4g [$ ' voltage their surrounding field strength may appreach the levels prevail- u. in - ce.n. - ' / w* ing near the right-of way of an HV line. The intuitive affirmative answer to the posed question could, to a N M M/ * ' M+ , -d*. D a-h s Y ~ "" " s,,. first approximation, derive theoretical support by.considering the house as a hollow object having a shell of some thickness, the material of ji
;pg;[ ..g .b.f) O 3 canter *=z ct.
which is sufficiently conductive such that current density in the shellis d
' ~. IU"' b" [Q~ !'
independent of its conductivity. Subjected to a uniform external field, ggae m , g y=:E yEfi g.), the internal field inside the shell is then related by Ohm's Law to be y ~"' u" = equal to the current density divided by the conductivity. Smce for any particular object, the current density will vary directly with the applied ,,,, p y ].~[p' O d , ,
, se fk.D external field, it follows that the internal field does likewise. Thus, if House #1 or #2 were located about 20 meters from the 500 kV conduc-p~,.
. w ,EM*(W@Qg ed O
M S*gr . 1 tors, the external undisturbed vertical field would be about 800 V/m in.
- stead of 80(Fig. Al or A2); and the measured average field inside the D 0,oco ts.] 9
't h
g ,qQQg3 houses may be expected to be ten times larger or 100 instead of 10 V/m. If this is so, one corollary result would be to modify the conclusion - ; Q %.m-7~~W.Ff*p@c-[N e --
** g E that the house power circuits are a significant part of the total field in. $ d.h'k,b" 84rf, 7 . . .,J side, since the inside field fue to them is no longer comparable to the magnitude of this field induced by the transmission line (Tables 1 and
.74 35 3 Mi b7-*@.4 A g,Ig3 If4'*
b.N.* r r, . -T ID, .
.4. w 3). Their generally subtractive effect on the line produced field in House ,
#2 indicated by Table I, and the additive effect in House #1 indicated by Field and Space Potential subsection of the MEASUREMENTS See-Table 2, would become a second order effect in determining the total tion. The unperturbed electric field at the rneasurement locations field strength inside the houses. (82.5m from the line for House I and 95m from the line for House 2)
Soliciting the authors' views on any of the above, we would at the can be found in Fig. Al. No specific effects of the house construction same time repeat a suggestion made to a few other parties on suitable or wiring were investigated. occasions in the last few years. This is to construct a test mock up of a No effort was made to change the arrangements in the rooms. Mea. house to allow much more comprehensise and controlled variable surements w cre taken in the same positions in the rooms for each of the measurements of fields both inside and outside than could possibly be " power-on/ power.off" conditions. Compared to a bare room, furni. made by sporadic efforts in a real inhabited house or in a number of ture and household effects can be expected to distort the field in phase such homes. The construction need not simulate a real house in all and magnitude. Varying construction such as wood, masonry, plaster respects. Prefabricated frame sections, exterior wall and roof panels board, aluminum faced insulation,ind so forth can distort the fiald as could be designed to permit non-permanent interconnections to form *CII. house shells of different shapes and different materials. No permanent The meter used has negligible proximity errors at distances greater foundation is needed. The mock up could be relocated, reassembled or than 20cm from the meter. The proximity effects of the operator were reoriented with respect to the fields at the test site, whether near an in. negligible due to the close spaced boundary conditions dominated by service line or some experimental test bne. We would venture that with the house and furnishings. some research. minded ingenuity, the cost and effort would not prove The measurements reported were a compromise between a simplistic extravagant relative to the value of the data which could be obtained. single position measurement in 3 axes and an extensive effort to thoroughly measure and describe the room fields as a series of three Manusenpt recewed February 25,1983. dimensional voltage surfaces. Fig. 6 in the paper was an exception where the single 52V potential was followed close to the house in a plane perpendicular to the house and the transmission line in retrospect we Stephen A. Sebo (The Ohio State University, Columbus, OH): The would have liked to try mapping the space potentials over the volume of authors are to be commended for their very interesting paper. Some the rooms. This can be accomplished with the EFM Model 110 field more information related to various aspects of the tests would be meter that we used. valuable for further reference: There is on-going work to more efficiently describe electric fields in
- 1. Can more details be given related to the meters and probes us@ household environment. There is usually a fairly urvform background l 2. Can more details be given related to the proximity effects that 1.e level. Sources are usually lamps and similar electrical devices. The l expected for tests conducted inside the homes? How were the sources are characterized as a radius surface, Ro, at a voltage, Vo, that meters (probes) positioned to minimize proximity effects? decreases radially as 1/R. This expression is:
- 3. In order to evaluate the field strength and potential at specific locations inside the homes, test locations, their relative positions Vsp = Vo Ro/R #
referring to the transmission line conductors, field strength com. , ponents, and som; other factors (e.g., phasing, grounding. R. G. Olsen: This discussion presents a concept to calculate the elec. shielding, construction, etc.) are essential. Would the authors tric field shielding of a buildmg. Rearranging the equations as a comment on these aspects of the test program? shielding factor yields: Manusens received March 3.1983.
- E 9\ (l ~ )
R. J. Caols D. W. Deno. V. S. Dymek: The helpful discussions point opt that this work was an initial effort. More data should be collected { " Q , g . (r) (g , f p r r
7g
., . If a
.. a. .
. g 3347 L a 4 '
work cf this paper tbserved a nominal shielding factor of 3:1 through c
- De consistency of the shielding factor would be dependent upon the roof. The outside field that penetrated these houses came mostly cipracteristics of the "shell tnaterial". It is possible that the dielectric through the roofs to the second story bedrooms.
properties of certain construction materials may vary depending on the V. Caleca: The question of the resistive linearity of common houses is magnitude of the electric field as posed in the first part of Mr. Caleca's important. Today we are in the habit of thinking of resistors as linear;~ ~. ~ - discussion. devices, yet some radio resistors build in the early 30s that had voltage' The shielding factor formula needs an interpretation that increase with current resembling a saw tooth. These resistors were not ~ sharacterizes a building's size R1, the wall-thickness Rt R2. and the much more sophisticated than wrapping wire about a penciliend for ter-wa!1s conductinty sigma. This formula was examined for practical ap- minals. This performance can be experienced in ordinary building con-plicat on. The conductivity sigma turned out to be unrealistically sen- struction, when no attention has been given to have resistive linearity. sitive. - The shielding factor equation assumes a homogeneousReal shell: When houses Indeed, in real resistive fields would give thenonlinearity is an best quality of data important conside Unfor-
- I the assumed material has a conductivity less than its permitivity reac- tunately these situations would not give sufficient data to empmcally tance, the conductivity has little effect. When practical materials get approximate properties such as nonlinnrity which would require ci damp and wet, their conductivity increases by many magnitudes greater plete voltage control of the power line. An experunental test s than the material permitivity reactance at 60 Hz, yet the shielding factor provide the voltage control environment. The choice of an e cf many structures do not change anywhere near as much as the inverse mock up would be tutjective, and would need substantiation as to cf the damp or wet material conductivity. This leads or the hypothesis applicability in dupbcating the grounding mesh effect, to v that most real frame houses have wallls and roofs more like variable- climates, to structural des'gn, to construction practices and so forth.
spaced coarse meshes or grids of highly varying material conductivity which da not shield anywhere near as much as a homogeneous material. These mesh apertures include windows and other conductive voids that Manuscript received May 23,1983. are hidden in the structural assembly of a house's walls and roof. The l O 0 h e
-. 4 um 9
l 1
.1 i
,l}}