Electromagnetic Testing - ECT Q&A

FIG. 5.32. Impedance diagram showing the signals from a shallow inside
surface flaw and a shallow outside surface flaw at three different frequencies.
The increase in the phase separation and the decrease in the amplitude of the
outside surface flaw relative to that of the inside surface flaw with increasing
frequency 2f 90 can be seen.
Phase separation
Charlie Chong/ Fion Zhang