Electroluminescence due to impulse voltage in cable-grade XLPE
Electroluminescence due to impulse voltage in cable-grade XLPE
复制标题
电缆级 XLPE 中脉冲电压引起的电致发光
DOI：
10.1109/94.775613
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发表时间：
1999
影响因子：
3.1
通讯作者：
A. Bulinski
中科院分区：
文献类型：
--
作者：
S. Bamji;K. Tohyama;A. Bulinski
使用中的地下电力电缆无意中受到雷电和开关浪涌产生的脉冲的影响，这些脉冲叠加在它们工作时的交流电压上。雷电和开关操作引起的高压瞬变不仅会辐射出大的电磁场，而且还会对绝缘施加额外的应力，并可能引发在正常工作条件下持续的劣化。高压电缆的电击穿是一种局部现象，聚合物绝缘局部部位的电老化是由于聚合物的分子解离和新化学键的形成而发生的。这个过程通常涉及分子的电子激发态，产生辐射现象，如电致发光（EL）。对电应力的分析可以帮助阐明发生在电应力增强点并导致电缆击穿的退化机制。EL技术比常用的局部放电检测灵敏几个数量级，可以更好地理解各种时间相关机制，如空间电荷注入、捕获和衰减，这些机制可能导致绝缘失效。本文描述了交联聚乙烯在脉冲电压作用下的电致发光特性。具有与交流电压半周期相同极性的脉冲叠加在其上，产生最大数量的EL脉冲。此外，当脉冲在正半周期和负半周期的峰值处施加时，比在交流电压的过零点处施加时发出更多的EL脉冲。这表明注入和捕获到聚合物中的电荷量对发光起着至关重要的作用。
Underground power cables in service are inadvertently subjected to impulses generated by lightning and switching surges that are superimposed on the ac voltage at which they operate. HV transients caused by lightning and switching operations not only radiate large electromagnetic fields but also impose additional stresses on the insulation and could initiate deterioration which can continue under normal operating conditions. Electrical breakdown of HV cables is a local phenomenon and electrical aging at local sites in the polymeric insulation occurs by molecular dissociation of the polymer and formation of new chemical bonds. This process usually involves the electronically excited states of the molecules that give rise to radiative phenomena, such as electroluminescence (EL). Analysis of EL can help to clarify the degradation mechanisms that occur at points of electrical stress enhancement and lead to cable breakdown. The EL technique is several orders of magnitude more sensitive than the commonly employed partial discharge detection and can provide a better understanding of the various time dependent mechanisms such as space charge injection, trapping and decay that can lead to insulation failure. The characteristics of EL in crosslinked PE subjected to impulse voltage, are described in this paper. Impulses having the same polarities as the half cycles of the ac voltage on which they are superimposed give rise to the largest number of EL pulses. Also, more EL pulses are emitted when impulses are applied at the peaks of the positive and negative half cycles than at the zero crossing of the ac voltage. This suggests that the amount of charge injected and trapped into the polymer plays a crucial role for EL emission.