On the 10th of June 2010 at 04:45 pm magnetic field measurements were performed for residence 5 Ilia Venezi Street in Larnaka and substation “Ermis”.
The substation is rated at a nominal power of 200 KVA. At the time when the measurements were performed, the substation load power was recorded as:
|
Red Phase |
Yellow Phase |
Blue Phase |
|
78A |
60A |
58A |
Table 1: Measured load current
The resultant load of all three phases was 23.5% utilization of the nominal load current.
Limiting exposure values have been provided by the ICNIRP recommendations and are guidelines to many countries and organizations. 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, E (V/m) |
Magnetic Field Strength, H (A/m) |
Magnetic Flux Density, B (µT) |
|
50 Hz |
10000 |
400 |
500 |
|
Reference levels for General Public exposure ICNIRP |
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|
Frequency |
Electric Field Strength, E (V/m) |
Magnetic Field Strength, H (A/m) |
Magnetic Flux Density, B (µT) |
|
50 Hz |
5000 |
80 |
100 |
Table 2: ICNIRP Exposure limits for Occupational and General Public exposure
The maximum obtained values from the investigation are represented below and compared to the ICNIRP specified limits of General Public and Occupational standards. The highest magnetic field measurement inside the residence was observed in the bedroom No 1. The measured value at this point was 0.257 µT and a percentage of 0.26 % as compared to the ICNIRP General Public standard. A detailed description of the maximum measured magnetic fields inside the residence is shown in the following table.
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Residence Field Measurements |
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Measurement Point |
Maximum Magnetic Field (µT) at Z Height /m - Percentage of ICNIRP General Public Standard /% |
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|
0.3m |
ICNIRP % |
1m |
ICNIRP % |
1.75m |
ICNIRP % |
|
|
Residence - Linving Room |
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|
Measurement Point C |
-- |
-- |
0.15 |
0.15% |
-- |
-- |
|
Residence - Bedroom 1 |
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|
Measurement Point D |
-- |
-- |
0.26 |
0.26% |
-- |
-- |
|
Residence - Bedroom 2 |
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|
Measurement Point E |
-- |
-- |
0.15 |
0.15% |
-- |
-- |
Table 3: Residence Maximum Magnetic Field Measurements - Inside area.
Furthermore the highest magnetic field measurement in the outside area was observed in the front side of the substation at a distance of 3 m along the field measurement line and at a height of 1.75m. The measured value at this point was 6.108 µT and a percentage of 6.11% as compared to the ICNIRP General Public standard. Accordingly a detailed description of the maximum measured magnetic fields in the outside area is shown in the table below.
|
Outside Field Measurements |
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|
Distance from Side /m |
Maximum Magnetic Field (µT) at Z Height /m - Percentage of ICNIRP General Public Standard /% |
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|
0.3m |
ICNIRP % |
1m |
ICNIRP % |
1.75m |
ICNIRP % |
|
|
Residence Garden - Above underground cable |
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|
Measurement Point A |
0.21 |
0.2% |
-- |
-- |
-- |
-- |
|
Measurement Point B |
0.14 |
0.14% |
-- |
-- |
-- |
-- |
|
0 m from substation front side |
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|
0 m |
2.62 |
2.62% |
4.52 |
4.52% |
6.11 |
6.11% |
|
1 m from substation front side |
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|
1 m |
0.44 |
0.44% |
0.52 |
0.52% |
0.44 |
0.44% |
|
2 m from substation front side |
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|
2 m |
0.22 |
0.22% |
0.21 |
0.21% |
0.20 |
0.20% |
|
0 m from substation left side |
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|
0 m |
0.43 |
0.43% |
0.35 |
0.35% |
0.42 |
0.42% |
|
1 m from substation left side |
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|
1 m |
0.11 |
0.11% |
0.13 |
0.13% |
0.09 |
0.09% |
|
2 m from substation left side |
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|
2 m |
0.11 |
0.11% |
0.13 |
0.13% |
0.08 |
0.08% |
|
0 m from substation back side |
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|
0 m |
0.29 |
0.29% |
0.30 |
0.30% |
0.22 |
0.22% |
|
1 m from substation backside |
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|
1 m |
0.22 |
0.22% |
0.26 |
0.26% |
0.12 |
0.12% |
|
2 m from substation back side |
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|
2 m |
0.19 |
0.19% |
0.21 |
0.21% |
0.12 |
0.12% |
Table 4: Maximum Magnetic Field Measurements - Outside area