Eddy-current defect test instrument with multiple test probes and one distance probe

An eddy-current test instrument having a rotary head provided with at least two test heads including eddy-current test probes offset mounted along a circular track for scanning a part to be tested;

• signal processing devices by means of which defect signals in the test probes are derived from defects in the part to be tested and wherein such defect signals are further processed;
• evaluation units wherein defect signals are evaluated;
• distance compensation devices wherein defect signals are compensated with respect to the distance h between the test probes and the part to be tested, including a distance probe wherein a distance signal is derived from the distance h, a signal processing device wherein the distance signal is processed to a control signal, and control elements connected between the signal processing devices and the evaluation units, said control elements modifying the defect signals as a function of control signals, comprising:
• a single distance probe and one signal processing device;
• means for providing control signals derived during one revolution of the distance probe identifying the peripheral position of said distance probe and storing the control signals in a first table (I);
• and
• means responsive to a test probe passing a peripheral position for retrieving the control signal for this peripheral position and for controlling the control element(s) belonging to the respective test probes of said test head by the retrieved control signals.