ESCO Technologies ETS-Lindgren HI-3702, Руководство пользователя, Страница: 17 / 25

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FUNCTIONAL THEORY OF OPERATION
Following is a functional theory of operation for the HI-3702 Clamp-on Induced
Current Meter. The objective is to enhance user understanding of the theory
behind the design to aid with the operation and maintenance of the HI-3702.
Theory of Operation
The HI-3702 is designed to measure RF induced current flowing through the
ankles or arms of the body under test, even while walking or climbing. The fiber
optically coupled readout/control unit does not perturb the measured RF field or
the current distributions.
The sensor is a ferrite split core current transformer. The signal generated by the
sensor is amplified by 10 dB to 50 dB depending on the range that is selected.
There is 20 dB of linearity for each range. This signal is applied to a True RMS
Thermal RMS to DC Converter. The DC voltage output of the True RMS Thermal
RMS to DC Converter is applied to a 12 bit A/D converter. This digital representation
of the DC voltage is read by the microprocessor, converted to a number that is
representative of current being sensed, and transmitted through the fiber optic
interface to the HI-4416 Digital Readout/Control Unit.