| 摘要 |
PROBLEM TO BE SOLVED: To detect magnetic metal foreign matter from an insulator with high sensitivity in cases when a non-magnetic metal portion is included in the insulator of a transformer lead wire connection, etc.SOLUTION: According to an embodiment, a method for detecting magnetic metal foreign matter inside an insulator involves detecting, from an object to be inspected that comprises a conductor and an insulator for covering the surface of the conductor, magnetic metal foreign matter that is included in the insulator, the method including a step for disposing a coil on the surface of the object to be inspected adjacent thereto, applying a high-frequency magnetic field of 1 kHz or higher from the coil to the object to be inspected, and detecting a magnetic field generated between the coil and the object to be inspected by using magnetic field detection means disposed between the coil and the object to be inspected. The method further includes a step for specifying the thickness of the insulator from the correlation of the magnetic field with the thickness of the insulator in the object to be inspected, and a step for applying a static magnetic field corresponding to the thickness of the insulator from the coil to the object to be inspected and detecting magnetic metal foreign matter buried in the insulator in the object to be inspected. |
