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Public magnetic field exposure based on internal current density for electric low voltage systems
Tommi Keikko1, Reino Seesvuori, Martti Hyvönen
1Tampere University of Technology, Department of Electrical Energy Engineering, P.O. Box 692, FI-33101 Tampere, Finland.
Health Physics
|March 12, 2009
Summary
A new magnetic field metering system for indoor substations measures exposure according to international guidelines. This system simplifies exposure assessment by relating basic magnetic field quantities to load currents, aiding in public and worker safety evaluations.
Area of Science:
- Electrical Engineering
- Health Physics
- Electromagnetics
Background:
- Indoor substations transform medium to low voltage, potentially exposing workers and the public to magnetic fields.
- Existing magnetic field measurement methods can be complex and demanding.
- International guidelines, such as those from the International Commission on Non-Ionizing Radiation Protection (ICNIRP), set exposure limits.
Purpose of the Study:
- To develop and validate a novel magnetic field exposure metering system for indoor substations.
- To enable direct comparison of measured magnetic field exposure with established safety limits for internal current densities.
- To analyze the behavior and dependencies of magnetic fields and exposure levels around substation components.
Main Methods:
- Development of a new magnetic field exposure metering system adhering to ICNIRP guidelines.
- Measurement of magnetic field values, total harmonic distortion, exposure ratios, and load current characteristics.
- Long-term magnetic field measurements within indoor substations.
- Analysis of relationships between measured quantities and substation load currents.
Main Results:
- The developed system effectively measures various magnetic field and load current parameters.
- Long-term measurements revealed complex and unanticipated correlations between different measured quantities.
- A simplified approach was demonstrated, substituting complex exposure measurements with basic quantity assessments (e.g., 50 Hz fundamental magnetic field component).
Conclusions:
- The new metering system offers a practical solution for assessing magnetic field exposure in indoor substations.
- The findings facilitate a more straightforward evaluation of compliance with non-ionizing radiation safety standards.
- The study highlights the potential to estimate exposure based on fundamental magnetic field components and load currents, simplifying safety assessments.
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