A Study on the Electromagnetic Inspection of Large-Diameter Ropes

为了评估悬架屋面、悬索桥中缆索等大直径固定钢丝绳的劣化程度，研制了两套电磁检测仪系统。这些仪器磁化绳子的原理不同。用于测试直径达60毫米的绳索的一个带有一对环形磁极的电磁管，用于纵向磁化绳索至饱和状态。另一个用于直径达95毫米的绳索，利用两个与绳索同轴的螺线管线圈，沿着被检查的绳索更有效地感应磁场。这些仪器中的检测器单元具有双环形霍尔效应元件阵列，用于检测由绳索缺陷引起的空间泄漏通量的径向分量。每个环形阵列被划分为六个圆周段，并且可以提取所述段的单个输出以定位所述绳索横截面中的缺陷。使用该仪器对悬挂式屋面中的PWS电缆进行了检查，并检查了所获得的检查记录。研究结果表明，这些仪器对大直径固定绳索的检测是有用和有效的。通过引入新的解释方法，用检测记录的横截面积损失来估计所测钢丝绳的劣化程度，电磁检测估计的横截面积损失与钢丝绳的实际面积损失非常接近。

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.