In order to reduce the effect of exposure to the electromagnetic fields a new legislation was finally introduced in Europe : the European directive 2004/40/CE, then modified by directive 2008/46/CE, was introduced in 2013. These regulations fix the limit values of electromagnetic fields generated by industrial machines as the induction melting plants and the employer is obliged by national law to apply these directives.
With reference to the above mandatory guidelines, the Italimpianti Orafi has equipped its induction furnaces with particular systems for the concentration of the scattered electromagnetic flux through a special metallic screen with the purpose of changing the spatial configuration of the electromagnetic field and increase the value of the same inside the crucible.
Example of application for a 150 kW induction furnace during the melting of precious metal at full power.
Reference is the exposure limit value according to the German standard BGV B11
(8 hours for 5 days a week): 67 μTesla
Limit distance ‘d’ is measured from the edge of the box that contains the coil towards the operator side measured with Electric and Magnetic Field Analyzer EHP-50C 5Hz – 100kHz
- without concentrators: 100 cm
- with concentrators: 30 cm
It means a reduction of almost 10 times of the surface area over the exposure limits.
In practice the presence of flux concentrators makes all the space around the coil accessible to the operator while in the case of the system not equipped with such devices makes it in fact not operational.
MAIN ADVANTAGES OF MAGNETIC FLUX CONCENTRATORS:
- Improvement of the conditions of health and safety in the working area
- Reduction of heat radiated to the operator and the environment
- Increase the life time of the plant
- Increase the energy efficiency
- Reduction of electric consumption up to 30%
- Reduction of melting time