The paper substantiates the need to use non-contact conversion and measurement of large direct currents using non-destructive magneto modulation non-contact ferromagnetic transducers of increased sensitivity for the needs of land reclamation, irrigation, industry, metallurgy and, in general, agriculture and water management; the results of their design development are presented. It is shown that the developed converter, in contrast to the known ones, has increased accuracy and sensitivity, a technologically advanced design and small weight and dimensions with low material consumption and cost. The issues of reliability of magnetic modulation contactless converters are considered. The results of their research have been obtained. It is shown that the reliability of wide-range magneto modulation contactless converters of large direct currents is equal to 0.998 and taking into account catastrophic failures, their total reliability is 0.9969. The developed converter can be widely used in electrical systems in land reclamation and irrigation, in water supply, industry, railway transport, science, technology and for checking electrical meters at their installation site.