Eddy current testing is one of the many NDT (non-destructive testing) method, it is applied electromagnetics theory as the basis of the conductor detection. The eddy current generated from a called electromagnetic induction phenomenon. When the AC power is applied to the conductor, such as copper wire, a magnetic field will be in the space of the guide body and surrounding the conductor generates a magnetic field. The eddy current is induced in the current, which flows in a loop. The reason is called "eddy", is an obstacle since it is surrounded with a liquid or gas flowing form is the same as in the loop. If a conductor is placed in the change of magnetic field, the eddy current will be generated in that the conductor, and the eddy currents will generate their own magnetic field, the magnetic field with AC current rise and expansion, as the AC current decreases blanking. Therefore, when some of the changes in the nature of the conductor surface or near-surface defects or to measure the metallic material will affect the intensity and distribution of the eddy current, so that we can work together to detect changes in the eddy current, and thus can indirectly know the inside of the channel title whether the presence of a defect and the metallic properties changed.

The eddy current as an NDT tool of the big advantages is that it can do a variety of inspection and measurement. In appropriate circumstances, the eddy current can be used:
1, crack, defect inspection
2, the material thickness measurement
3, the coating thickness measurement
4, material conductivity measurement

 

The superiority of the eddy current testing mainly include:
1, the sensitivity for small cracks and other defects
2, the detection of surface and near surface defects speed, high sensitivity
3, the test results are instant
4, device interface
5, requires only a few preparatory work
6, the test probe does not require contact with the analyte
7, we can check the shape and size of the complex conductor