Low-frequency magnetic shielding (MuFerro)

MuFerro is suitable for magnetic shielding in frequency ranges from DC to 100 kHz and is optimized for 50/60 Hz. MuFerro-FS (MF-FS) combines permeability and saturation characteristics which makes it extremely suitable for screening low-frequency magnetic fields. MuFerro-ECFS (MF-ECFS) enhances these characteristics with eddy current performance. MuFerro has a sheet size of 2000 x 1000 x 0,66 mm.

Why use magnetic shielding/screening?

Magnetic fields pose a serious threat to human health and wellbeing. For instance, research has shown that exposure to magnetic fields of > 300nT or 0.003 Gauss significantly increases a person's chances of developing leukemia. There are numerous other physical symptoms associated with exposure to magnetic fields, e.g. headaches, depression and insomnia. For this reason the Health and Safety Codes in many countries recommend that for working spaces exposure should be < 0.5 μT=500 nT and for public spaces it should be < 0.1 μT=100nT. Apart from their negative impact on health, strong magnetic fields can cause interference or damage to electronics in the immediate vicinity of where the field is generated. Magnetic fields also interfere with sensitive measurements in hospitals and laboratories.

Measurement

Before the screening/shielding is ordered and installed, we can conduct a site survey (magnetic field strength measurement) for you. We not only measure the magnetic field strength, but also locate its probable source. The measurement results are then presented in a report.

Applications

• Transformer rooms (indoors or outdoors)
• Power plants
• Aluminium melting / production
• High current applications that create strong magnetic fields
• Scientific lab
• Busbars / cabling
• Reduction of field-values to below exposure limitation recommendation

Holland Shielding Systems B.V. can implement magnetic shielding even after the transformer has been put into place. For screening entire buildings, or rooms, the shielding material is applied to walls, ceilings, and/or floors. This protects both people and electronics.

Checklist for quotation request

To make a good estimate for the electromagnetic shielding you need, we kindly ask you to provide the information below. This helps us create a suitable proposal for the right shielding measures. Not sure about something or missing some details? Just let us know: we are happy to work it out together.

Drawings & Dimensions

• Cross-sectional sketch or drawing
  With global dimensions of the setup
• Distances between source and areas to be protected
  Horizontal, vertical and/or diagonal

Situation & Areas

• Location of areas to be protected
  Indicate whether these are above, next to or below the source

Technical data

• Current (in amperes)
  Or the specified kVA capacity of the transformer
• Type of transformer
  For example dry transformer, oil-filled, etc.
• Type of busbar
  For example aluminium or other metal, IP68 with epoxy/casting resin, manufacturer and type

Based on the data provided, we map the radiation pattern of the magnetic field. If certain information is not (yet) available, we can make an estimate based on experience.
Do you have any questions or is certain information missing? No problem: we are happy to think along with you.

Customer benefits

• Cost-effective solution
• Up to 95% field-strength reduction or more
• Flexible design
• Measurement report

MuFerro combines permeability and satiety characteristics which makes it extremely suitable for screening low-frequency magnetic fields.

Medical facility for example MRI rooms

Buildings with high current/voltage cables

Transformer rooms and power plants

Scientific lab / DC shielding

Shielding Characteristics

The effectiveness of shielding is expressed as the shielding factor. Different configurations will give different results in shielding effectiveness. MF-FS can be applied in multiple layers to increase the shielding factor. MF-ECFS is spotwelded on location to create a uniform shield.

MuFerro shielding material ensures that magnetic fields are kept within a safe radius around the electrical equipment.

Magnetic field before applying MuFerro

Magnetic field after applying MuFerro

Holland Shielding Systems B.V. can implement magnetic shielding even after the transformer has been put into place. For shielding entire buildings or rooms, the shielding material is applied to walls, ceilings and/or floors. This protects both people and electronics. Before the shielding is ordered and installed, we can conduct a site survey (magnetic field strength measurement) for you. We not only measure the magnetic field strength, but also locate its probable source. On request, the measurement results are presented in a report.

Example projects

Example project 1
Due to space restrictions, one of our clients was forced to turn a room which had formerly been used for storage into an office space; this room was located on the floor above power transformers. However, powerful magnetic fields were noticed in that room which made the computer displays flicker, so we were asked to carry out a magnetic field measurement. It was found that the magnetic field strength was far above the standard referred to above - it was 750 nano Tesla. This magnetic field was reduced by the installation of an umbrella construction of MuFerro™. Since completion of this project, the magnetic field has been reduced to only 80 nano Tesla.

Below are some images of heavier transformer shields for military and medical applications where a very high reduction needed to be achieved.

The clients who have engaged us to place MuFerro shielding include: