Interference

Without external magnetic shielding, much of today's sophisticated electronic gear would be larger, less efficient and in some magnetic environments, unlikely to function correctly.

Magnetic Shielding

Magnetic shielding assures optimum performance for many types of equipment - electron microscopes operating in a sensitive mode, MRI magnet systems, electromagnetic diagnosis equipment using SQUID technology, nuclear cameras, computers, VDU's, ultrasound equipment, tape drives and magnetic tapes to name a few. 

Shielding is accomplished by placing a high permeability material between the field source and the sensitive components affected. Such material must be conductive to prevent passage of electric fields and highly permeable to prevent passage of magnetic fields. Shielding materials commonly used have a permeability range of 300 to 500,000, depending on flux density. 

Magnetic Field Interference Products and Services

Without external magnetic shielding, much of today's sophisticated electronic gear would be larger, less efficient and in some magnetic environments, unlikely to function correctly. As components are made more sensitive and packaging more dense, susceptibility to electromagnetic interaction increases dramatically even in the best engineered layouts. 

Electromagnetic interference can originate from various sources. These could include permanent magnets or electromagnets, coil components such as transformers, solenoids and reactors, AC or DC motors and generators, and cables carrying large DC or AC current at power frequencies. In many cases, even the earth's normal magnetic field can affect proper functioning. 

Computer Centres

Computer installations need to be shielded where ambient interference levels are high such as radar pulse or electrical transient radiation. RFI specialises in this field and will construct modular or all welded steel enclosures to suit the purpose. Dependent upon attenuation requirements, a lower cost enclosure can be fabricated, utilising special foil application techniques. Raised computer floors, acoustic treatment and air conditioning can also be provided.

Shielded Rooms for Electron Microscopes

RFI Industries offers a range of standard modular magnetic shielded rooms of typical sizes 3.0 x 4.0m with heights of 2.4m and above. 

The shielding panels are laminated with a number of layers of high permeability steel to achieve the desired shielding capability. Special considerations in design are given to door entries, ventilation, lighting, cable penetrations and vibration mounting requirements.

Ambient Field Strength Surveys

RFI Industries will carry out field surveys to establish ambient field strengths. This is normally essential to calculate the shielding thickness required to avoid saturation. Field surveys or investigations can also help in discovering "that mysterious interference" to a computer system or distortion on the VDU screens.

VDU Shielded Enclosure

There are many possible solutions to magnetic interference problems. Basically, either the device sensitive to the interfering field or the field source may be shielded. In typical monitor shielding situations, the source may be strong and occupy an extensive area, making source shielding difficult to design and very expensive. Relocation of the sensitive equipment to an area free of interfering fields may also be possible. For an easier solution, consider a shielded monitor enclosure. 

High Permeability Foils

Many magnetic shielding problems can be solved with a pair of scissors and a sheet of magnetic foil. The foil is hand trimmed to the required outline and fitted around the structure to be shielded. Measurements then tell whether refinements are needed. Satisfactory ductile foil material, ranging from 0.002 to 0.01 in thick, is available in various permeability ranges. 

Shielding of Bus Bars and Power Plants

It is necessary in some cases to provide shielding of bus bars or high current carrying conductors. These conductors produce high magnetic fields which will cause interference to adjacent electrical or electronic equipment e.g. V.D.U.'s, Television sets or Medical Electronic Devices. RFI Industries can design and supply shielding ducts or shielding in plant rooms using high permeability steel or mu-metal materials. .