The effect of the electrical resistivity of conductive copper connections on the reliability of testing the soldering quality of clamp side walls by the amplitude eddy current method

A transformer eddy-current transducer with rectangular notches in the poles of its U-shaped core is used to study the effect of a change in electrical resistivity of M1 copper within the range between 0.01724 and 0.01748 μΩ∙m according to GOST 193-79 and GOST 1173-2006 on the error in determining the soldering quality of the side walls of clamps with lead ends of current-carrying rods, which are used to connect stator windings in state-of-the-art designs of hydro- and turbogenerators. Specimens made at different times and received from different power engineering enterprises are studied. It is found that, when the relative difference of electrical resistivity varies within 1.36%, the error in evaluating the level of soldering of the side walls of clamps does not exceed 15.5%. This must be taken into account when performing eddy current testing.