Non-destructive testing device for elongate conductive metal object using eddy current technique has measuring element provided by segmental measuring coils overlapping at their ends

摘要

The testing device has a measuring element radially enclosing the tested object (1), e.g. a pipe, provided by 3 segmental measuring coils (6,7,8), connected as strip conductors in a difference or multi-difference circuit. The ends of the segmental measuring coils overlap one another in the peripheral direction, the measuring coils enclosed by an absolute coil (11), in turn enclosed by an energizing coil (12).