| 摘要 |
<p>An eddy current probe for detecting defects in a tube comprises bracelets of multi-coil units around a housing. Each unit comprises one transmitter coil (T) and a pair of receiver coils (+R1, -R1) electromagnetically polarized in opposite directions, arranged to produce a differential output. The probe detects localized defects and is capable of detecting defects of any orientation even in regions of localized tube deformations; however, it is specifically suited for detecting circumferential cracks in the tube. The probe is particularly suited for the detection of circumferential cracks. Each pair of receiver coils can be connected separately thereby resulting in a multi-channel output and each of the transmitter coils can be connected to a separate transmitter energiser. <IMAGE></p> |
