Mechanical Fatigue as a Mechanism of Water Tree Propagation in TR-XLPE
Mechanical Fatigue as a Mechanism of Water Tree Propagation in TR-XLPE
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DOI：
10.1109/tdei.2012.6148534
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发表时间：
2012-02-01
影响因子：
3.1
通讯作者：
Wright, Paul K.
中科院分区：
文献类型：
--
作者：
Wang, Zuoqian;Marcolongo, Piero;Wright, Paul K.
本文报道了与地下电缆绝缘水树发育有关的树状阻燃剂交联聚乙烯（TR-XLPE）的疲劳失效研究。有限元计算用于估计电缆绝缘中由双电泳力产生的应力；这些应力在长而细的包裹体（或水树枝）周围的低兆帕斯卡范围内。它们不足以引起绝缘的瞬时失效。然而，这些应力可能足以引起绝缘的循环疲劳失效，因此，对商业电缆的样品进行了疲劳测量。由此产生的疲劳失效，发生在实际工作中可以达到的周期数，表明疲劳可能是水树在地下服役多年后发育缓慢的一个解释。在较高的机械应力、较高的温度和腐植酸或铁离子存在下，失效时的循环数较低；然而，在有水的情况下，失败的循环次数更大。
The paper reports on an investigation of the fatigue failure of tree retardant cross-linked polyethylene (TR-XLPE) that is relevant to water tree development in underground cable insulation. Finite element calculations were used to estimate the stresses developed in cable insulation by di-electrophoretic forces; these stresses are in the low megaPascal range around inclusions (or water tree branches) that are long and thin. They are insufficient to bring about instantaneous failure of the insulation. However, these stresses might be sufficient to cause cyclic fatigue failure of the insulation, and, accordingly, fatigue measurements were carried out on samples from a commercial cable. The resulting fatigue failures, that occurred at cycle numbers achievable in practical work, suggest that fatigue might be an explanation for slow development of water trees over years of service in the ground. Cycle numbers at failure were found to be lower at higher mechanical stresses, at higher temperatures and in the presence of humic acid or ferric ions; however, the number of cycles to failure was larger in the presence of water.