Naslov
Istodobno mjerenje više parametara metalne cijevi metodom jedne zavojnice
(Single-coil method for simultaneous measurement of multiple parameters of a metal tube)

Autori
Vasić, Darko

Vrsta, podvrsta i kategorija rada
Ocjenski radovi, magistarski rad

Fakultet
Fakultet elektrotehnike i računarstva

Mjesto
Zagreb

Datum
30.11

Godina
2005

Stranica
120

Mentor
Bilas, Vedran

Ključne riječi
nondestructive evaluation; eddy-current method; remote-field technique; single-coil method; tube properties measurement; coil impedance; electronic instrumentation; high-temperature environment

Sažetak
Eddy-current methods are the nondestructive methods of choice for the measurement of tube properties: inner radius, wall thickness, relative magnetic permeability and electrical conductivity. Eddy-current systems, that measure tube properties from the interior of tube (e.g. in oil-wells), employ multiple excitation frequencies and several coil pairs. Reduction in number of coils and frequencies can improve the reliability of such systems. In this master's thesis, analytical models have been derived of the magnetic field distribution and impedance of a coil placed axially inside a tube. A procedure has been proposed for correction of thickness measurement for changes in electromagnetic properties. Permeability measurement has been shown to be applicable to tube grade identification and stress evaluation. The single-coil method has been presented for simultaneous determination of inner radius and permeability-to-conductivity ratio. This is achieved through minimization of difference between the model prediction and the measured impedance of a single coil at a single frequency. The method reduces total number of coils and frequencies required. In order to confirm practical realizability of the method, sensitivity analysis has been made with respect to tube properties and coil dimensions. Due attention has been paid to other influential factors, such as temperature, material non-idealities, coil decentralization, etc. The experimental results, obtained for several tubes, validate the proposed procedure. Further improvements of the method have been proposed. Requirements for the single-coil system have been established relating to operation in a high-temperature environment, ranges of tube properties to which the system is applicable, and accuracy of radius measurement. An electronic instrumentation design has been proposed for the single-coil system.

Izvorni jezik
Engleski

Znanstvena područja
Elektrotehnika

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