Design and Evaluation of Measuring System for ELF Magnetic Fields

초록

With the three dimensional magnetic field measuring system dealt with in this paper, accurate measurements and analyses fo ELF magnetic field caused by starting and/or operating electric devices can be conducted. To obtain high performance for lower frequency and spatial components without any distortion the measuring system is designed with the multiturn loop-type magnetic field sensors, differential amplifiers and active intergrators as three dimensionally. As a result of calibration experiments, the frequency response characteristics of the measuring system range from 8Hz to about 53kHz for each direction of x, y, z axes, and the response sensitivities are 9.54, 9.21, 10.89mV/uT, respectively. The actual survey by using an oscillating impulse current generator confirms a reliability of the proposedmeasuring system. Also, through another experiments by using small-sized induction motors, the magnetic field intensities decrease steeply according as the measuring distance from radiation source increases.