| 摘要 |
The device is designed to apply an electromagnetic field to a target. The device has a core (1), two groups of excitation windings (2,3) and measuring windings or magnetic field sensors (4). The excitation windings of one of the two groups are superposed on those of the other group so their axes are orthogonal and their coils cross each other in an orthogonal fashion on at least a non-negligible common surface which forms an active surface used for fault detection. The excitation windings and the smallest segment of the smallest active surface is less than or equal to 0.1. The cores (1) is rectangular shaped for plane targets and is a tube for tubular targets. The core has a shape which similar to the target surface to be controlled. The core is made from a magnetic material of magnetic permeability relative greater than 1 and of low electrical conductivity.
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