Demagnetizing machines produce alternating electromagnetic fields which act on people and devices in the immediate vicinity. The term electromagnetic alternating field covers the magnetic field and the electric field (both field coexist according to Maxwell’s equations in the case of temporally variable electromagnetic fields).
The electric field can usually be neglected with regard to personal protection on demagnetizer equipment powered directly by the mains voltage range (up to 480 VAC). The alternating magnetic field is of importance.
Magnetic fields decrease disproportionately with increasing distance from the source. Magnetic fields can be effectively shielded with magnetically highly permeable sheets.
Exposure limit values have been defined for electromagnetic fields to ensure personal safety. It must be distinguished between international recommendations, EU directives and regulations:
- ICNIRP: International Commission on Non-Ionizing Radiation Protection; International recommendation
- 2013/35/EU: European directive electromagnetic field – personal safety
- BGV B11: “Berufsgenossenschaftliche-Verordnung” for electromagnetic fields (Germany)
All these recommendations and regulations have frequency dependent limit values in common. At lower frequencies, higher limits are allowed.
The operator triggers the demagnetization at the power module at a safe distance (typically 1…2m) from the coil, when using a controlled demagnetizer. This simple measure is sufficient in most cases to safely fall below even the strictest limits. The manual passage of parts through a conventional demagnetizing coil, on the other hand, hardly corresponds to a contemporary view of personal protection, since the worker is too close to the coil.
Persons with heart pacemakers and other body aids are subject to separate regulations, with stricter limits.
- BGI/GUV-I 5111: Accident prevention regulations for persons with physical aids (Germany)
EMC (electromagnetic compatibility):
The immunity to interference and the interference of equipment and machines with regard to electromagnetic fields are governed by EMC regulations.
- 2014/30/EU: European Directive