Investigation of planar coil for eddy current conductivity measurements in wide frequency range

Peer Reviewe

Practical Precision Electrical Impedance Measurement for the 21st Century – EMPIR Project 17RPT04 VersICal

The core objective of EMPIR project 17RPT04 VersICaL is to improve the European measurement infrastructure for electrical impedance, with particular emphasis on the capabilities of developing NMIs and calibration centres. The project will seek to exploit the results of existing research on digital impedance bridges (DIBs) by designing, constructing and validating simple, affordable versions suitable to realise the impedance scale in the range 1 nF to 10 μF and 1 mH to 10 H with relative uncertainties in the range 10-5 to 10-6. The first results of the research project, including the bridge designs and details of a polyphase digitally synthesized multichannel source capable of providing voltage outputs of precise ratio and phase are presented

Investigation of planar coil for eddy current conductivity measurements in wide frequency range

Peer Reviewe

Inhomogeneity Correction in Calibration of Electrical Conductivity Standards

The method for inhomogeneity investigation of measurement standards for electrical conductivity has been studied in the conductivity range from 2 MS/m to 14 MS/m. For this purpose a planar spiral coil has been developed and characterized. The impedance values of the coil are measured in the air and with a conducting plate above the coil at discrete frequencies from 2 kHz to 70 kHz. By selecting the corresponding operating frequency, relative changes in the conductivity value throughout the sample thicknesses have been measured. It was revealed that inhomogeneity of measurement standards has an effect on further measurements with calibrated conductivity meters. The relative conductivity changes of 0.1% due to inhomogeneity can be detected with the measurement uncertainty (k = 2) of less than 0.3% of the measured value

Investigation of Planar Coil for Eddy Current Conductivity Measurements in Wide Frequency Range

Several planar coil designs have been investigated for the application in accurate AC conductivity measurements in the wide frequency range. The measurement method is based on the eddy-current probe-coils solutions proposed by Dodd and Deeds [1]. The coil parameters affecting the performance of the model in the specified frequency range from 30 kHz to 720 kHz have been investigated. Different designs have been used including coils on a printed circuit board (PCB), coils on a flexible substrate and on-site manufactured coils winded from a copper wire. The goal was to reach the inductance of the different coils to match the best-accuracy of the measuring instrument. Amongst the others, the important factor was to keep the diameter of the coils suitable for the practical applications

Precise Eddy Current Impedance Measurement of Metal Plates

Properties of conductive materials can be characterized and validated by electrical conductivity. Eddy current measurements have many benefits as compared to 4-point contact measurements. Combining theoretical and experimental studies have shown that with single planar spiral coil absolute measurements can be carried out with accuracy less than 10%