Primary converters of electromagnetic field for nondestructive testing of underground service lines

We formulate basic requirements for the technical characteristics of primary converters for nondestructive testing and technical diagnostics of underground service lines. A classification of primary converters used in magnetic and eddy-current methods of nondestructive testing and in electromagnetic control and diagnostics of underground service lines is proposed. It is shown that passive induction converters, due to a number of their unique properties, are the most suitable for methods and equipment of nondestructive testing and technical diagnostics of underground service lines. The spheres of efficient use of induction, flux-gate, Hall, and mechanical converters in devices for control and diagnostics of underground service lines are outlined in accordance with the frequency range of magnetic fields under measurement.