Small integrating meter for assessing long‐term exposure to magnetic fields

Publisher Website
Google Scholar
Abstract
A small, lightweight meter has been developed for magnetic‐field measurements, particularly those needed for exposure‐assessment purposes. This meter, known as the AMEX‐3D, continuously measures all three axes of magnetic‐flux density and electronically combines the data into a single estimate of cumulative exposure to the root‐mean‐square (rms) resultant flux density. The AMEX‐3D weighs about 120 g, measures 2.7 cm x 5.1 cm x 10.2 cm, and is battery powered. Two panel‐mounted jacks are provided for measuring battery voltage and for reading cumulative exposure data from the unit. The instrument has, within 3 dB, a flat response to magnetic flux densities at all frequencies in its 30–1,000 Hz bandwidth. A detailed analysis of error sources in the AMEX‐3D leads to an estimate of ±20% as the accuracy of the instrument over its dynamic range, which extends from 0.02 to 15 μT. The AMEX‐3D was tested in the field by asking electricutility distribution linemen to wear AMEX‐3D and EMDEX meters simultaneously while working. Agreement between the two measures of exposure was excellent. 1992 Wiley‐Liss, Inc.