Through-Coil Arrangement, Test Apparatus with Through-Coil Arrangement and Testing Method

摘要

A feed-through coil arrangement for an apparatus that tests long products via eddy current includes an exciter coil arrangement with an exciter coil having a passage opening for the long product, and a receiver coil arrangement around the opening. The receiver coil arrangement includes two segment coil arrangements distributed over the passage circumference, wherein each segment coil arrangement has a detection range covering only a circumferential section of the long product circumference. The segment coil arrangements are distributed over two shells surrounding the opening at different distances to a reference axis. First segment coil arrangements on a first shell are without reciprocal overlapping and second segment coil arrangements on a second shell are without reciprocal overlapping. The first and second segment coil arrangements are arranged circumferentially offset to one another such that the second segment coil arrangements detect circumferential sections not covered by the first segment coil arrangements.