Exposure Modelling of Extremely Low-Frequency Magnetic Fields from Overhead Power Lines and Its Validation by Measurements
Abstract
:1. Introduction
2. Materials and Methods
2.1. Model
2.1.1. Calculation Methods
2.1.2. Load Data
2.1.3. Geometric Data
2.1.4. Error Estimates and Simplifications
2.1.5. Computations for Validation
- List of the coordinates of tower positions x and y (and later also z)
- Mast-schemas for all masts, one drawing per mast
- Drawings of isolators
- Phase-allocation schema for all circuits
- Graphics/tables on line sag, for all spans
- Load flow data (time, voltage, active power, and reactive power) as 15 min averages for the measurement periods and 1 h averages for the whole year 2015 from Swissgrid and in part also from BKW.
- Two different digital terrain models: (1) the DHM25 with 25 m resolution, and (2) the more precise model DHM5 with 5 m resolution.
- Model A: gives the arithmetic average using the 25 m resolution terrain model DHM25.
- Model B: gives the RMS mean using the 25 m resolution terrain model DHM25.
- Model C: gives the arithmetic average using the 5 m resolution terrain model DHM5.
- Model D: gives the RMS mean using the 5 m resolution terrain model DHM5.
2.2. Measurements
2.2.1. Selection of Sites for Validation
2.2.2. Measurement Procedures
- Emdex II. Seven devices were placed at distances 0 to ±40 m.
- Estec DL-MW10s. One device was placed at distance 0 m together with an Emdex II, and a second one was used as a spare and for spot measurements.
- Estec EMLog2e. Two devices were placed at ±80 m, as they have higher sensitivity and resolution than the Emdex II and DL-MW10s.
3. Results
3.1. Pilot Study
3.2. Modeling
3.3. Measurements
3.4. Comparison between Measurements and Modelling
Statistical Evaluation of Model Uncertainty
4. Discussion
5. Conclusions
Supplementary Materials
Acknowledgments
Author Contributions
Conflicts of Interest
Appendix A
Emdex II | ESTEC DL-MW 10s | ESTEC EMLog 2e | |
---|---|---|---|
Manufacturer | EMDEX-LLC (www.emdex-llc.com) | ESTEC (www.estec.de) | |
Measurement range | 300 μT | 130 μT | 10 μT |
Resolution | 10 nT | 10 nT | 1 nT |
Precision | ±3% (overall) ±10% (worst case) | ±3%, ±10 nT (one axis) | ±3%, ±1 nT (one axis) |
Axis-directions | Y-axis parallel to long side of devices | X-axis parallel to long side of devices | |
Frequency bands | Broadband: 40–800 Hz Harmonics: 100–800 Hz | 5–30 Hz 37–2000 Hz | |
Data rate | 1.5–327 s | 1 s | |
Battery-capacity 1 | ca. 90 h | 7 days | |
Number of data points, Recording-period 1 | 15,000 <62 h | 5,500,000 7 days | |
Power source | 9V Alkaline battery | Li-Ion, chargeable via USB-cable | |
Data storage | Data deleted on power-off | Permanent storage | |
Operating temperature range | 0–60 °C | 0–40 °C |
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Measurement Nr. | Site | Begin | End |
---|---|---|---|
M1 | Iffwil | 20 January 2015 13:30 | 22 January 2015 13:30 |
M2 | Wiler | 17 February 2015 14:00 | 19 February 2015 14:00 |
M3 | Iffwil | 24 March 2015 12:30 | 26 March 2015 12:30 |
M4 | Wiler | 8 April 2015 12:30 | 10 April 2015 12:30 |
M5 | Iffwil | 26 May 2015 14:00 | 28 May 2015 14:00 |
M6 | Wiler | 2 June 2015 14:00 | 04 June 2015 14:00 |
M7 | Iffwil | 7 July 2015 10:30 | 9 July 2015 10:30 |
M8 | Wiler | 28 July 2015 11:00 | 30 July 2015 11:00 |
M9 | Iffwil | 8 September 2015 12:30 | 10 September 2015 12:30 |
M10 | Wiler | 15 September 2015 13:00 | 17 September 2015 13:00 |
M11 | Iffwil | 27 October 2015 13:15 | 29 October 2015 13:15 |
M12 | Wiler | 8 December 2015 14:00 | 10 December 2015 14:00 |
Iffwil | Wiler | ||||
---|---|---|---|---|---|
Model A (for ) | DHM25 | −0.04 | 0.11 | 0.07 | 0.08 |
Model B (for ) | −0.04 | 0.11 | 0.08 | 0.08 | |
Model C (for ) | DHM5 | 0.02 | 0.09 | −0.01 | 0.08 |
Model D (for ) | 0.02 | 0.09 | −0.01 | 0.07 |
Near Points, | Far Points, | |||||||
---|---|---|---|---|---|---|---|---|
Model A (for ) | Model B (for ) | Model A (for ) | Model B (for ) | |||||
Site | ||||||||
Iffwil | −0.11 | 0.08 | −0.12 | 0.07 | 0.03 | 0.13 | 0.03 | 0.12 |
Wiler | 0.11 | 0.05 | 0.12 | 0.05 | 0.05 | 0.10 | 0.05 | 0.09 |
Near Points, | Far Points, | |||||||
---|---|---|---|---|---|---|---|---|
Model C (for ) | Model D (for ) | Model C (for ) | Model D (for ) | |||||
Site | ||||||||
Iffwil | 0.01 | 0.04 | 0.01 | 0.04 | 0.03 | 0.12 | 0.04 | 0.12 |
Wiler | −0.03 | 0.05 | −0.03 | 0.05 | 0.02 | 0.09 | 0.02 | 0.09 |
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Share and Cite
Bürgi, A.; Sagar, S.; Struchen, B.; Joss, S.; Röösli, M. Exposure Modelling of Extremely Low-Frequency Magnetic Fields from Overhead Power Lines and Its Validation by Measurements. Int. J. Environ. Res. Public Health 2017, 14, 949. https://doi.org/10.3390/ijerph14090949
Bürgi A, Sagar S, Struchen B, Joss S, Röösli M. Exposure Modelling of Extremely Low-Frequency Magnetic Fields from Overhead Power Lines and Its Validation by Measurements. International Journal of Environmental Research and Public Health. 2017; 14(9):949. https://doi.org/10.3390/ijerph14090949
Chicago/Turabian StyleBürgi, Alfred, Sanjay Sagar, Benjamin Struchen, Stefan Joss, and Martin Röösli. 2017. "Exposure Modelling of Extremely Low-Frequency Magnetic Fields from Overhead Power Lines and Its Validation by Measurements" International Journal of Environmental Research and Public Health 14, no. 9: 949. https://doi.org/10.3390/ijerph14090949