METHOD TO ASSESS QUALITY OF SOLDERED JOINT IN WINDINGS OF ELECTRIC MACHINES Russian patent published in 2016 - IPC G01N27/90 

FIELD: measurement equipment.

SUBSTANCE: invention relates to investigation or analysis of materials using vortex currents and may be used to monitor quality of soldered joints in windings of various electric machines (EM) during production and repair. The method to assess quality of a soldered joint of windings of electric machines consists in the fact that the joint is probed with a vortex current meter, for which purpose the excitation winding located at one side of the joint is used to develop a magnetic field, which is received by the coaxial measurement winding located at the opposite side of the joint. Received signal amplitude is measured. Prior to measurements the meter is calibrated, for which purpose they probe reference joints: non-soldered, fully soldered, and then the investigated joint. The quality of the investigated soldered joint of the electric machine winding is assessed, comparing amplitudes of the received signal with signals from reference joints. During probing of joints they additionally measure the phase of the received signal, during calibration they probe the non-soldered and fully soldered joints several times under various relative positions of the joint and windings of the meter. They calculate the position of the equidistant point of the complex plane, relative to which the amplitude of received signals does not depend on the relative position of the joint and windings both for non-soldered and soldered joints. To assess the degree of joint soldering they use ratios of amplitudes of received signals of reference and investigated joints, recalculated relative to the equidistant point.

EFFECT: increased accuracy of measurements; at the same time the process of measurements becomes invariant to accuracy of setting of windings and their dimensions relative to a soldered joint.

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