EDDY-CURRENT INSPECTION DEVICE Russian patent published in 1994 - IPC

FIELD: non-destructive inspection. SUBSTANCE: device has serially- connected generator, transformer-type eddy-current transducer with ferromagnetic core and feed-back winding, signal processing unit and indicator, reference-input element and comparison unit coupled with the reference-input element. The device is characterized by the use of a rectifier connected between the feedback winding and a signal input of the comparison unit, by the use of a current-to-voltage connected in an eddy-current conversion current circuit, by the use of digital-analogue converter, reversible counter and a control unit. The generator is made controllable. The comparison unit output is connected to the input of the control unit. The output of digital-analogue converter connected to the reversible counter is connected to the generator control input. The control unit is connected to the control inputs of reversible counter and digital-analogue converter and indicator. The feedback winding is arranged in aligned relationship with eddy-current transducer measuring winding. The signal processing unit is connected to the output of current-to-voltage converter and has controllable gain. The feedback winding and measuring one are identical and are formed by conductors of a common stranded wire. EFFECT: enhanced accuracy due to automatic adjustment of magnetic coupling between winding as a result of varying a current of generator with simultaneous correction of sensitivity to a parameter being measured. 3 cl