foer device to at virvelstroemsprovning of omagnetiska provobjekt detect and suppress the influence of stoerande magnetic omraaden

摘要

Device for eddy current testing of non-magnetic test objects (1), for example crack detection on hot continuously cast billets, for detecting and suppressing the influence of disturbing magnetic regions and/or magnetic material, such as cold oxide scales (2). The device comprises at least one transducer (3) adapted to move relative to the test object, with at least one detector (6) associated with the transducer, and serving to detect the possible presence of disturbing magnetic regions and/or material. At least one blocking circuit (7) is provided, controlled by the detector (6), for suppressing signals originating from a fault vector (FV), for example a crack signal. According to the invention also the magnetic regions and/or the magnetic material are/is adapted to be detected via eddy current technique, and the signals originating from a mu -vector are adapted to be separated from signals originating from a fault vector.