A Study on the Electromagnetic Inspection of Large-Diameter Ropes

点击翻译按钮获取中文摘要

In order to evaluate the degree of deterioration of large-diameter stationary wire ropes, such as cables in suspension roofings and suspension bridges, two systems of electromagnetic inspection instruments have been developed and constructed. These instruments are different in the principle to magnetize the rope. The one which is intended for testing the ropes up to 60 mm in diameter has an electromanget with a couple of annylar magnetic poles to magnetize the rope longitudinally to the saturation state. The other one for the ropes up to 95 mm in diameter utilizes two solenoidal coils coaxial with the rope, which induce magnetic field more effectively along the rope to be inspected.The detector unit in these instruments has twin annylar arrays of Hall effect elements to sense the radial component of spatial leakage flux derived from the defect in the rope. Each annylar array is divided into six circumferential segments, and the individual output of the segments can be extracted for locating the defect in the cross section of the rope.The inspection of PWS cables in a suspension roofing was carried out with the instruments, and the inspection records obtained were examined.As the result of this research these instruments have been recognized to be useful and effective for inspecting large-diameter stationary ropes. The deterioration of the rope under question has been estimated in terms of loss in the cross sectional area from the inspection records by introducing the new method of interpretation, and the cross sectional area loss estimated by electromagnetic inspection corresponded closely to the real area loss in the rope.