FMS Project:


EMI Conditions at site of new underground TEM Lab

EMI conditions at site of new underground TEM Lab from adjacent buried 12.5 kV transmission line. AC magnet field levels ranging from 1.2 to 2.5 mG greatly exceed required 0.1 mG EMI threshold for the TEM microscopes.

Shielding plan for underground TEM Lab rooms

Shielding plan for underground TEM Lab Rooms. Conductive shielding installed on floor ceiling and wall surfaces to provide a complete six side shield to provide < 0.1 mG environment. Isolation slabs for each TEM separately shielded on surface and four sides.

Conductive shielding is installed on inertia islolation blocks

Early in construction, FMS technicians installed conductive shielding on the top and sides of TEM Room’s inertia isolation block. The TEM microscopes are eventually installed on top of these large blocks which dampen vibrations and as such are isolated from the TEM Room structure.

Interior view of a TEM Lab room

Interior view of one TEM Lab room with conductive shielding installed on floor, ceiling pus all wall surfaces and a view of finished interior with TEM installed.

Precision AC magnetic fiels test & measurement equipment

To confirm anticipated reductions in AC magnetic field levels in each of the fully shielding TEM rooms, precision test and measurement equipment capable of making highly accurate measurements (within 1% at 60Hz for magnetic field strengths between 0.01 mG and 10 mG) was utilized.

AC Magnetic Field Measurements

Precision measurements taken after installation

Typical line plot of precision measurements taken after installation of conductive shielding in both TEM Room’s floor, ceiling and wall surfaces, confirms that AC magnetic field environments had been successfully reduced to levels < 0.005 mG…..significantly well below the target EMI threshold of 0.1 mG.


Over its 20 years, FMS has successfully completed hundreds of EMI projects which included a diverse range of consulting and mitigation services.

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