The shielding plates offered by Sati Shielding S.r.l. are multi-layer type consisting of conductive and ferromagnetic material. The different behaviour of the two materials results in a product with optimal shielding efficiency close to the source and maintains a good shielding factor even when moving away from it.
The orientation of the shielding plates compared to the “field source Magnetic“, is crucial for mitigation. From Theoretical analysis also supported by experimental testing it is suggest ed that the placing of the plates with the ferromagnetic part facing towards the source ensures a better shielding efficiency only If that is at few centimeters from the shield and in the case in which is carried a complete shielding of the room where the sources are. Therefore we recommend this type of installation only in the case where the “Victim” is very close (few cm) to the shield.
In all other cases the best performances are obtained with the shielding material with high conductivity facing the “source” and the ferromagnetic to the “victim”.
This is related to two factors which may be summarized as follows:
1)The conductive material operates on the principle of creating a magnetic field which is opposed to the source field, through the currents induced in the same. And therefore it is appropriated that the conductive material refer to the higher source field. If we orient the plate with the side of the ferromagnetic material to the source, this reduces the operating effect of the conductive material.
2) The efficiency of a screen is linked to the magnetic and electric continuity of the shielding plates. Failure to link of the plates with on the conductivity face, greatly reduces the overall shielding features, because the induced currents that create the reverse field can only circulating in the single plate and can’t move between a plate and the others. It is therefore essential an electrical connection between the plates, using profile or welding.
The negative effects due to conductive and ferromagnetic discontinuity can be in the practice emphasised by inevitable installation tolerances that can generate significant gaps (several millimetres) between the plates on large surfaces. These gaps generate an increase in the effects on the conductive and ferromagnetic shields and make welding operations between the conductive parts even more complex.
Wanting to maintain the advantages inherent in the concept of the modular plate, Sati Shielding has developed a new product, which improves the problems mentioned with regard to the conductive and ferromagnetic parts.
The flat plate is usually square-shaped with one part of the sides flat and the other moulded to form a wing. The wings of a plate will overlap with the flat parts of the adjoining wings. Installation of the different plates is as shown in Fig. 13.
The proposed solution enables the following advantages:
a) Reduction in magnetic coupling reluctance between the plates. Consider having a mixed system of conductive and ferromagnetic plates. In the area where the lower and upper plates overlap, the magnetic field passes from one ferromagnetic plate to another through the thickness limited to the conductive layer (Fig. 15).
b) Compensation of edge effect on magnetic fields due to induced currents in the edges of the plates. As shown in Fig. 16, the induced currents in the two plates have opposite direction and therefore generate local magnetic fields that mutually compensate each other. This compensation is an advantage regarding the effects to the edges, even without welding.
c) By welding the conductive plates the induced current are not confined in each single plates and this correspond to an increase in the performance of the shielding system. In fact, welding restores electrical continuity between the plates, thus enabling the induced current to circulate freely. Welding carried out between the edge of the upper plate and the flat part of the lower plate (Fig. 17) is facilitated by the natural recovery of mechanical tolerances in connection with overlapping between the plates. This facilitates the installation phase of the plates and enables increased margins on mechanical tolerances.
d) Infine, la presenza della sovrapposizione tra le piastre agevola la fase di installazione delle piastre a soffitto. Fissata una prima piastra superiore a soffitto, quella successiva di tipo inferiore può utilizzare l’ala della superiore come base di appoggio.
The proposed solution can be used on plates made from different compositions of ferromagnetic and conductive plates, and therefore on the entire range offered by Sati Shielding.