High Voltage Overhead Power Lines - 21 Georgiou Eikosari, Dali
On the 22nd of July 2009 at 17:30 pm, electric and magnetic field measurements were performed for 21 Georgiou Eikosari, Dali overhead power lines. The EMF measurements were performed inside and outside the residence and in direct proximity to the overhead power line.
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The transmission towers are tall steel lattice structures that support overhead electricity conductors for power transmission. The overhead power line is rated at a nominal power of 900 MVA. At the time when the measurements were performed, the load of the overhead power line was 142 MW and 20 MVar. The Resultant Load of all three phases was 15.93 % utilization of the nominal load power.
Limiting exposure values have been provided by the ICNIRP recommendations and are guidelines to many countries and organisations. The exposure limits at 50 Hz are tabulated in the following table according to the limits given by ICNIRP.
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Reference levels for Occupational exposure ICNIRP |
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Frequency |
Electric Field Strength |
Magnetic Field Strength |
Magnetic Flux Density |
|
50 Hz |
10000 |
400 |
500 |
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Reference levels for General Public exposure ICNIRP |
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Frequency |
Electric Field Strength |
Magnetic Field Strength |
Magnetic Flux Density |
|
50 Hz |
5000 |
80 |
100 |
Table 1: ICNIRP Exposure limits for Occupational and General Public exposure
The maximum obtained values are represented below and compared to the ICNIRP standards for the General Public. The highest magnetic field value inside was observed in the 2nd bedroom of the residence, with value 1.80 μT and a percentage of 1.80 % as compared to the ICNIRP General Public standard.
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Overhead Power lines: Inside Field Measurements |
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Measurement Point |
Maximum Magnetic Field (µT) at Z Height (m) |
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0.3m |
ICNIRP %
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1m
|
ICNIRP % |
1.75m
|
ICNIRP %
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Measurements inside the residence
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Measurement Point A - 1st bedroom |
-- |
--
|
1.64
|
1.64% |
--
|
--
|
|
Measurement Point B - Bathroom |
-- |
-- |
1.48 |
1.48% |
-- |
-- |
|
Measurement Point C – 2nd bedroom |
-- |
-- |
1.80 |
1.80% |
-- |
-- |
|
Measurement Point D – 3rd bedroom |
-- |
-- |
1.67 |
1.67% |
-- |
-- |
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Measurement Point E – Living room |
-- |
-- |
1.31 |
1.31% |
-- |
-- |
|
Measurement Point F – Dining room |
-- |
-- |
1.16 |
1.16% |
-- |
-- |
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Measurement Point G - Kitchen |
-- |
-- |
1.30 |
1.30% |
-- |
-- |
Table 2: Maximum field measurements inside
Accordingly, the highest magnetic field outside was observed below the overhead power lines, with a value 1.70 μT (0 m away from the starting point) and a percentage of 1.70 % as compared to the ICNIRP General Public standard..
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Overhead Power lines: Outside Field Measurements |
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Measurement Point |
Maximum Magnetic Field (µT) at Z Height (m) |
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|
0.3m |
ICNIRP %
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1m
|
ICNIRP % |
1.75m
|
ICNIRP %
|
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Measurements inside the residence
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Measurement Point H |
-- |
--
|
1.22
|
1.22% |
--
|
--
|
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Measurement Point I |
-- |
-- |
1.44 |
1.44% |
-- |
-- |
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Measurements along the Overhead Power Line |
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30m Measurement Line |
1.3 |
1.30%
|
1.29
|
1.29% |
1.7
|
1.70%
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Measurements across the Overhead Power Line |
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30m Measurement Line |
1.14 |
1.14%
|
1.26
|
1.26% |
1.34
|
1.34%
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Table 3: Maximum field measurements outside area