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Title
Verfahren zur Bestimmung der elektrischen Leitfähigkeit an Proben mittels eines Wirbelstromsensors
Date Issued
2014
Author(s)
Joneit, Dieter
Patent No
102013004990
Abstract
An eddy current sensor is used to excite an electrical alternating field with a known measurement frequency f, [omega] inside a sample, and an electromagnetic alternating field is thereby formed, which is detected with a detector and the complex impedance Z = R + jX is determined. This procedure is carried out at different measurement frequencies f, [omega] once in air and once with the same measurement frequencies f, [omega] on a calibration body having a known electrical conductivity [sigma]. Then the differences between real and imaginary part [Delta] [R] and [Delta][X] of the values in air and on the calibration body are divided by the respective measurement frequency f, [omega], each pair of values [Delta][R]/[omega] and [Delta][X]/[omega] = [Delta] [L] being assigned a product [omega][sigma] in accordance with the associated measurement frequency [omega] and the known conductivity [sigma] of the calibration body, and said value pairs are used to plot an [omega][sigma] locus curve in a Nyquist diagram.
Language
de
Patenprio
DE 102013004990 A1: 20130319