Non-contact current measurements
Authors:   Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, Lviv, Dzhala M. 
Published: December 2024

The monograph is devoted to the actual and practically important scientific and technical problem of non-contact diagnostic examinations of underground (and underwater) pipelines (UP) and other current-carrying communications. The results of theoretical and experimental studies and scientific and technical approaches to the development of new methods and devices for non-contact current measurements (NCM) and their applications for UP diagnosis are presented. The main stages of the development of contact and non-contact methods of measuring currents without breaking an electric circuit are described.

Non-contact electromagnetic (EM) examination methods have significant advantages over known contact electrometric methods in terms of efficiency and informativeness. But they needed more advanced methods and appropriate special equipment. For their creation at the Physical and Mechanical Institute named after G. V. Karpenko of the National Academy of Sciences of Ukraine carried out a complex of research works and technical developments: the informative signs of the EM field of UP and their connections with the parameters of the structure were investigated; the measured characteristics of the field were selected and the algorithms for determining the parameters of the control object were established; appropriate NCM tools were developed and a new method of UP examinations was tested in real-world conditions; algorithms and recommendations for the interpretation of measured information and a new technology of diagnostic examinations and testing of the technical condition of anti-corrosion protection of UP according to NCM have been developed.

The monograph consistently sets out the theoretical justification of the NCM method with a description of the proposed new methods and devices and the characteristics of the developed hardware and the results of field tests and practical use. The main stages of the development of the theory of electric currents and methods of their measurement are briefly described. The theory of the EM field of UP, informative features of the magnetic field of currents is described. NCM methods and devices, EM method and means, and the information and measurement system of UP diagnostic examinations are described. Examples of the use of NCM are given.

The theoretical basis of NCM methods is the proposed triune mathematical model (TUMM) of the EM field of UP, which is based on the solutions of boundary value problems of electrodynamics, the theory of electric circuits with distributed parameters and the theory of spatial distribution of current fields. Informative features of the EM field of UP and anomalies of its distribution were studied.

New methods of gradient, parallax and invariant NCM UP, new NCM methods and devices are proposed, and their classification and areas of rational application are given. The technical characteristics of new effective devices created at the PMI of the National Academy of Sciences of Ukraine for UP examinations are given. As a result of their hardware implementation, a method and means of monitoring and a new technology of surveys of the state of anti-corrosion protection of anti-corrosion protection of UP according to NCM have been developed. The results of their field tests and practical use on main pipeline routes and pipeline networks that transport gas, oil, water, and chemical industry products are given.

The experience of practical use of NCM for integral, differential and local diagnostic examinations and control of the condition of insulating coatings and electrochemical protection against corrosion of UP and related metal structures is described and analyzed. It is shown that NCM provides the possibility of quantitative estimations of the “pipe-ground” transition resistance and its components – ground, insulation and polarization resistances. According to NCM, it is also possible to determine the specific resistance of the insulating coating in different sections of the UP with a resolution up to the length of the UP section commensurate with the depth of its occurrence. NCM detect the places of UP insulation damage and the most probable places of corrosion. The use of NCM makes it possible not only to increase the efficiency and informativeness of diagnostic examinations, but also to reduce labor costs.

The monograph is intended and will be useful for scientists, specialists and students in the fields of information and measurement systems, electrodynamics, non-destructive testing and technical diagnostics, anti-corrosion protection, inspections and operation of pipelines and related underground metal structures.