Draeger Medical Systems Inc.
EMI/RFI Site Testing, Utility & LV Electrical Distribution Simulations & Impact Analysis, EMI/RFI Shielding Designs, Fabrications & Installation & Final Commissioning
Vitatech preformed an EMF human health and exposure assessment for the Drager Medical Systems office building located in Andover, Massachusetts. A full-spectrum site survey was preformed in occupied areas to determine if AC ELF magnetic field levels were hazardous to office workers and staff. During the assessment, magnetic flux density levels of (10-99 mG) were recorded within and around stacked electrical closets. Of particular interest, was a 1000 kVA exterior transformer located 10 feet from the building with a peak magnetic flux density level of 972 mG, joining underground 480/277 V secondary feeders to the main electrical room (MER).
With respect to the general IRPA & ACGIH magnetic field thresholds (833 mG, and 1000 mG) for general population human health exposure requirements, the building fully complied with all occupied areas. Vitatech’s human exposure and EMI immunity threshold of 10 mG, adversely reflects two decades of research and development in a variety of markets such as residential, commercial, university, research and medical. Since epidemiological studies point to an increased cancer risk at even lower levels, a case can be made for recommending 1 uT (10mG) and 100 V/m as levels not to be exceeded in prolonged human exposure. Under normal building conditions the electrical switch-gear loads can be expected to increase from 50% to 80% full capacity in which prudent avoidance is strongly recommended. Simulated emissions on the south-east corner for the 1st floor determined that a vast majority of the space exceeded the 10 mG electromagnetic interference (EMI) threshold for electronic equipment and Vitaech’s recommended 10 mG thresholds for long-term human exposure.
Vitatech was commissioned to design and install an AC ELF magnetic shielding systems to attenuate the levels emitting from the the main electrical room (MER) and the underground secondary feeders. The outside transformer however, was not mitigated due to the presence of a large window.